286 J O H N C A M E R O N

cally the space where the .i-arious ‘missing links’ would have to fit in.

LITERATURE CITED

1 CAMERON, JOHN 1925 The craxio-facial axis of Huxlep, pt. 11. Tr. ROT. Soc. Can., third series, XIX.

THE PITUITARY-BASION-XASlON ANGLE

A N E W C R A N I A L ANGLE. ITS S I G N I F I C A N C E IN M h N , THE

ANTHROPOIDS. A N D LOWER M A M M A L S

CRANIOMETRIC srrurms, NO. 7

PART I. ITS SIGATIFICANCE IN M A N

The pituitary-basion-nasion angle is included between lines connecting the basion with the nasion and the pituitary point. The other two constituent angles of the triangle N.P.B. have been already discussed in Craniometric Studies, nos. 5 aiid 6. As the title of the present communication indicates, the angle P.B.N has not been previously described. It was found that this angle bears a definite relation to the ‘main angle of cranial flexion,’ which is the angle K.P.B. The writer has previously shown(1) that the latter aiigle gradually di- minishes in size as one ascends the mammaliaii series, until it reaches its minimum dimensions in the white races. He has likewise pointed out that the other two constituent angles of the triangle N.P.E. must gradually increase in size as one ascends the evolutionary scale. This gradual increase has been already demonstrated in the case of the P.N.R. angle in Craniometric Study, no. 6. The purpose of the present com- munication is to prove the existence of this gradual increase in the case of the P.R.N. angle.

This angle was estimated in the way detailed in Cranio- metric Study, no. 6, aiid it may be added that the same pre- cautions were again observed. The same material was util- ized, namely, 153 male American white crania, 153 male American negro crania, 51 female American white crania, and 37 female American negro crania.

CRANIOMETBIC STUDIES 287

The pitui tary-basioii-iiasioii angle reached its maximum arerage dimensions in the male American white, the figure Being 27". I n this group of crania the aiigle exhibited the usual wide range of racial variation, namely, from the maxi- mum of 37" to a minimum of 17". The minimum average size of the angle, namely, 24.5", was found in the female American negroes. In this cranial group the range of variation was from a maximum of 31.5" to a minimum of 12.5". The range of variability in the case of the female American whites was from a maximum of 33" to a niiiiimum of 18", and in the male American negroes from a maximurn of 33.5" to a minimum of 11".

TABLE 1

Showing that the pitztztury-basio?i-na.s~o~L angle reaches zts mintntzcm size in t h . 3 American aegro, both male and female. Xhe maximvna .uire i s

shown b y the male American whzte Yrnimptwc Martmuni

Malc American negro, 11" 33.5"

Xale American white, 17" 37" Female American white, 18" 33"

Female American negro, 13.5" 31.5"

As in the case of the pituitary-nasion-basion angle, this angle was found to reach its minimum size in the Americaii iiegro crania, both male and female, as representing the lower racial types. This is shown in table 1, and it may he suggested that the figures displayed there will gain added significaiice when studied in conjiinctioii with the mammalian list ill table 4. For example, the lowest ehb, viz., ll", as found in the American negi-o actually compared unfavorably with the figure yielded by a chimpanzee skull, which was 12.5"

An investigation of the average sizes of this angle, as given in table 2, shows that these were lower in the females than ill the males, both white and negro, axid it may be noted that this was exactly the condition found in the case of the pitn- itary-nasion-hasioii angle (Craniometric Study, no. 6) . It may he further remarked that, in the case of both angles, the Teason fo r this was the same, ilarnely, owing to the fact that the main angle of cranial flexion, the largest constituent angle

288 J O H N CAMERON

of the triangle N.P.B., was ascertained to be of greater dimen- sions in the females of both races. A further study of table 2 will disclose the fact that the average of 27" for the male American white is two degrees greater than that for the male American negro, while the average of 26.5" for the female American white is exactly two degrees greater than that for the female American negro. We thus find a remarkable example of sexual consistency, just as in the case of the pituilarp-nasioii-basion angle. Moreover, it will be observed from table 2 that the average size of the angle in the male american white is half a degree greater than that for the female American white, and it is larger to exactly the same extent in the male American negro as compared with the female American negro. Here, just as in the case of the pituitary-nasion-basion angle there is displayed a rather striking example of racial consistency.

TABLE 2

Showang that the avrrage swes of the pituztary-basion nasson angle are lower zn the females than t n the males both wkzte and negro, and t o

exactly the some extent in both race8

Female American white, 26.5"+0.3182 Male American whit?, 27" rf;0.1876 &Pale American negro, 25" 20.21008

Female American negro, 24.5"-t0.4501

It was pointed out in Craniometrie Study, no. 6, that tlie standard deviations and the coefficieiits of variability of the pituitary-nasion-basion and the nasion-pituitary-basion angles displayed an interesting parallelism. In both instances the standard deviations and the coefficients of variability were higher in the negro crania, this condition, moreover, being consistent f o r the two sexes. The same parallelism was found in the case of the pituitary-basion-nasion angle. These are all displayed in table 3. A further study of this table shows that the numerals are remarkably near one another for the males and females of both races-6.9 and 6.8, 5.06 and 5.03, 5.9 and 6.1, 4.4 and 4.6, 2.84 and 2.76, 3.27 and 3.20, 13.20 and 13.8, 15.95 and 16.84, 3.43 and 3.37, 3.54 and 4.06, 12.70 and 12.71, 15.36 and 16.56. The high coefficients of variability for the pituitary-nasion-basion and Pitcitary-basioii-iiasioii

CRANJOMETRIC STUDIES 289

angles are explained by the smallness of their size which iiaturally increases the amount of personal error during the execution of the measurements.

TABLE 3

Skowiibg th,nt t h e staiiularcl d a ~ i a t i o n s and the coeflcients of variability of the pitu,itar~-nnsion-Baswr~, i~asion-piliiitary-basion, and the pituitary-basion-

nasioiz angles are higlier i n the negro crania, both male and female P.2V.B. ,angle A'.P.R. ang1.e P .B.N. ang le

s. n. c. of 8. s. D. c. of v. s. I). c. of v. Female negroes, 3.30 16.84 6.94 5.06 4.06 16.56 Male negroes, 3.27 15.95 6.8 5.03 3.84 15.36 Female whites, 2.76 13.80 5.96 4.44 3.37 13.71 Male whites, 2.84 13.20 6.11 4.64 3.43 12.70

PART 11. COMPA4RATIVE ANATOMY

The comparative anatomy of the pituitary-basioii-nasion angle proved to be a profitable field of study. The tabulated results are shown in tahle 4 . The most important aiid signi- ficant result obtained was a gradual increase in the numerical value of the angle, as oiie ascended the mammalian scale, until it filially reached its maximum dimensions iii the white races, just as in the case of the pituitary-nasion-basioa angle. From the Carnivora downward it is a minus quantity, like the pituitary-nasion-basioii angle, and for exactly the same reason, namely, that the pituitary point is actually helow the nasion-hasion line in these lower types. I n other words, the triangle 3T.P.B. is reversed.

TABTA 4

Showzng l7iat tn lower mammalian forms f h r p?l?~llnry-nnsson-baszon and t h c pituztary-basaan-nnszon angles do not exzst, aad that there zs a gradual and progresswe ancrease an t h e w swes us we puss upward through the anthropoids and the 9 ~ ~ p - o race, untal the maximum 1s rcaul~rd 271 the whtte races

Pituilory-7kn~sio~i-bnsion angle

Dog, minus

Gibbon, 0.75" Gorilla, 0.75" Chimpanzee, 8.5" Orang, 8.5"

Lemur, 0.5"

Female nrgro, 19" Male negro, 20.3" Female white, 20" Male white, 21.5"

P ~ t u i t a ? 11 bns ion -nas ion ang le

Dog, minus Lemur, 0.5" Gibbon, 1.25" Gorilla, 1.25" Orang. 10.5" Chimpanzee, 12" Female negro, 34.5O Male negro, 23"

Male white, 27" Female whitr, 26.5"

290 JOHN C4MEELON

The most sigiiificaiit phase in the evolution of the pituitary- hasioii-nasion angle was found in the lemurs. In Lemur catta, for example, thc writer ascertained that the pituitary point had just crossed the nasion-basion line, aiid had, indeed, become raised above it t o the extent of 1 mm. Therefore, the first suggestions of the existence of the pibuitary-basioii- iiasioii angle and consequently of the flexion of the cranio- facia1 axis upon itself were found in the lemurs, thus placing them in a most important position iii the evolutioiiary scale.

The gradual raising of tlic pituitary point above the nasioii- basion line becomes more and more maiiifest as we ascend the Primate group. A study of the pituitary-basion-aasion angle in the gibbon showed that this animal occupied its cor- rect evolutionary position as the lowest type of the aiithro- poid group, f o r it was ascertained that the size of the angle was merely 1.25' ; that is to say, only 0.73 of a degree greater than that of Lemur catta. The writer was, however, sur- prised at the small size of the angle in the gorilla skull, for it measured only 1.25", the same as in the lowly gibbon. The sizes ascertained in the cases of the orang and chimpanzee, namely, 10.5" aiid 12", respectively, were very much greater, though still dccidedly below the dimensions found in the negro and white races, as table 4 shows.

A suggested explanation for the anomalous position occu- pied by the gorilla, which is generally acknom-ledged to be the most highly evolved member of the anthropoid group, has been already furnished by the author in Craiiiometric Study, no. 6. Therefore, it is unnecessary to dilate further upon that topic here.

It is now opportune that attention be directed to the very evident evolutionary gap which exists between the anthro- poids and the human series (in- table 4). The existence of this gap has been already emphasized in the cases of the nasion-pituitary-basion and the pituitary-nasion-basion angles. ?%Te are thus provided with further additions to the already vast accumulation of evidence which shows the immeiise hiatus separating Homo from his iiearest relatires

291 CRANIOMETRIC STUDIES

amoiig the Primates. Indeed, the writer has become more and more coiiriuced of this fact since 1le took up the suhject of craniometry. Palaeontology has thus a hard task ahead of it in attempting to fill in the iiumerous steps that are awanting in the evolutionary ladder.

The minimnm dimensions of the pitujtary-~asioii-iiasioii angle in the white and negro crania, however, were found to approximate to those found amoiig the aiitliropoids, thus teiidiiig to fill up the evolutionary hiatus mentioned in the preceding paragraph. For example, the low minimum of 11" found in the male A4mericaii negro (cranium 110. 6G2) com- pared uiifavorably with the chimpanzee (table 5). Moreover, the low minimum of 12.5" found in female American iiegro cranium no. 545 was r e ry slightly better. The minima f o r the white crania were likewise fairly low. The minimum for the male whites as found in craiiium no. 930 was only liG, and f o r the female whites 18", as measured in craiiium no. 675. These facts are recorded iii table 5.

TABLE 5

Showing that t h e niiximiiiii sizes of t h e pitititary-bnsioii-)i.asion angle in, lhle

t h a t the l&?Ql.o types e&ib,ited Lower minvima ihnn the wh,ite.s Hominidae ? m y approximale t o those f o m d in the anthropoids. N o t e

Gibbon, 1.25' Minimum in female American

Orang, 10" Minimum in male American Minimum in male American n l i i t e! 17"

11 egro, 11" Minimum in female American

Gorilla, 1.15" negro, 12.5"

Chimpanzee, 11" white, 16"

The present craiiiometric study is a fittiiig sequel to Craniometric Studies, nos. 5 a id 6, for it prorides a third index proving the existence of a gradual flexion of the cranio- facial axis upon itself. The earliest suggestions of this flexioii are found in the lemurs, just as in the case of the nasioii-pituitary-basion and the pituitary-nasion-basion angles. I t gradually becomes more and more pronounced as one ascends the anthropoid group, and finally attains to its maximum in the white races of mankind.

292 J O H N CAMERON

CONCLUSIONS

1. The pituitarl\.-basion-nasioii angle is an index of cranial flexion.

2. It does not exist in lower mammals. 3. It makes its first appearance in the lemurs. 4. It gradually increases in size in the anthropoid group. 5 . It reaches its maximum size in the white races, in which,

therefore, cranial flexion likewise attains to its maximum. 6. It exhibits remarkable sexual consistency and also racial

consistency, when studied in the American white and the American negro.

7. It evidently possesses wide ranges of variation in lower mammalian types, as in man.

8. It is evident that there is likewise a sexual factor which determines the size of the angle.

9. As regards the size of this angle, a vast evolutionary gap exists between the anthropoids and man. This is logi- cally the space where the various ’missing links’ would have to fit in.

LITERATTRE CITED

1 CAMERON, JOHN 192.5 The cranin facial axis of IIuxley, pt. 11. Tr. Roy. Sne. Can., third series, XIX.

CORRELATION BETWEEX THE TWO ANGLES CRASIOMETRIC STTJDIES, No. 8

The present communication deals with the question as to whether anj7 correlation exists between the two new cranial angles that were described in the sixth and seventh Cranio- metric Studies. It may be stated at once that an unusually favorable correlation was found to exist between these two cranial angles.

The crania examined were similar in numbers to those utilized in the sixth and seventh Craniometric Studies and were divided into the same four groups-male Americaii white, female American white, male L4merican negro, a i d fe- male American ncgro.