392 A Study of the Nasal Bridge in the Anthropoid Apes 
it have been possible to bring together even the slender numbers now dealt with, 
and a very full sense of our obligations to these gentlemen must here be 
expressed. 
In a recent paper entitled "A Study of the Negro Skull" (Biometrika, Vol. VIII. 
pp. 315 — 320) a special study was made of the nasal bridge in the Congo and 
Gaboon crania and the results compared with measurements on Egyptian and 
English series. There resulted values so suggestive that a wider study was 
promised, and that promise is to some extent fulfilled in the present paper. 
In the former paper it will be remembered that the chord from dacryon to 
dacryon (DC) was measured — the mesodacryal chord — and the minimum arc from 
dacryon to dacryon (DA) — the mesodacryal arc. The ratio 100 (arc — chord)/chord 
was termed the mesodacryal index (3. If on the other hand we measure the 
subtense of the minimum arc (DS) and take the index 100 subtense/chord, 
we obtain a second mesodacryal index, which we will term here the mesodacryal 
index a. As a cannot be found without a special instrument, or a special 
construction, an attempt was made to determine the second mesodacryal index a 
from the first jS by the hypothesis that in man the bridge of the nose may be 
sufficiently closely represented by a catenary, which seemed a fairly justifiable 
assumption in this case. The index thus indirectly found will be termed in this 
paper the mesodacryal index a'. Tables to determine a from /3 calculated by 
one of us (Julia Bell) were published in the same number of Biometrika, 
pp. 338 — 9, as the paper on the negro skull. An extension of these Tables due 
to H. E. Soper, rendered necessary when we deal with apes, will be found in the 
footnote on p. 401 of the present paper. Meanwhile our attention was drawn by 
Professor G. D. Thane to Merejkowsky's pioneer work of 1882 on the nasal bones. 
He measured the shortest horizontal chord from nasal suture to nasal suture (SC) 
and the minimum subtense (SS) and took the index 100 SS/SC, which we have 
ventured to term the Simotic Index, S. There is little doubt that this index is 
of a more simple anatomic character, as being only concerned with the nasal bones, 
than the mesodacryal indices. But it is by no means so marked a physiognomic 
feature in the living as the mesodacryal index. It has further to be obtained by 
aid of a special instrument — in our case a modified Merejkowsky instrument, — 
which may be termed the simometer. This simometer may also be used to test 
the relationship between observed a and calculated a. 
In the present investigation a, /3, S have been measured and a calculated for 
Gorilla, Chimpanzee, Gibbon and Orang. But in the case of the latter ape it 
was found possible to measure the simotic index in only a few cases, — the index 
taking frequently the form of the ratio of two almost vanishing quantities*. In 
* There were three eases in which the simotic chord was recorded among the Orang-utans. In two 
males it was 5 - 7 and 5-8 mm. In both these cases the subtense was zero, for the bones were practically 
fiat; thus the simotic index was zero. In the third case, a female, the simotic chord was 7'0 mm. and 
the subtense 1-2 mm. and therefore the simotic index was 17T. There were a few further cases in which 
the chord only was measurable. Thus on the basis of such isolated cases we should have to place the 
Orang-utan below the Chimpanzee, and both of course below the Negroes. 
