Kathleen V. Ryley and Julia Bell 
393 
the Orang the nasal bones are fused into a narrow flat strip from 5 to 6 mm. wide, 
sometimes there is only a thread at the nasal bridge or the nasals are entirely 
absent. In some cases the maxillary bones stand out forming a ledge which over- 
hangs the region of the dacryon and extends beyond it, thus making it very difficult 
to measure with Merejkowsky's instrument. Initially we excluded entirely from 
our measurements the Gibbon, but notwithstanding the difficulties of including 
this ape, it afterwards appeared to us that it might be worth while to indicate 
the results in rough numbers. The difficulties partly arise from the fact that a 
large proportion of the Gibbon crania available are without any statement as to 
sex and we did not feel that an attempt at sexing would be really profitable, as 
the total numbers were not large enough to give double series. Further we are 
compelled to distinguish between Hylobates and Symphalangia, and even of the 
former with the sparse data as to locus usually provided, it is impossible to assert 
that we are dealing with anything like a homogeneous race. Thus we found 
ourselves ultimately with only 25 cases — c? + ? + 3 — Hylobates — indeed only 16 
for the simotic characters, and 9 cases — c£ + ? + 3 — SympJialangus — with merely 
six for the simotic characters. Our results in this case can therefore only be 
rough indications of the racial characters of the nose of these apes. Our Museums 
have yet to learn that for comparative study we want at least 50 to 100 crania 
of each sex drawn from definite districts. To compare with those of the apes 
the corresponding indices were measured in a number of human races selected in 
order to contrast the values, if possible, with those of the anthropoid apes of the 
same continent. A few other human races are taken to indicate general relation- 
ships. The Hindoo, Egyptian and English crania used ai*e at University College 
either in the Biometric Laboratory or in the Department of Anatomy ; the 
Asiatic skulls and the Congo skulls are at the Royal College of Surgeons; the 
Gaboon skulls at the British Museum of Natural History. The nasal features of 
the latter as well as of the English and Egyptian crania had already been 
discussed in Dr Crewdson-Benington's paper referred to above. 
(2) Reliability of Measurements. 
The first point to be considered is the degree of reliability in the measure- 
ments made, and here we must again emphasise the difficulty of accuracy. Not 
only do the quantities measured differ by their extreme smallness from the 
customary cranial measurements, but the points for measurement and the 
instrument for measurement are by no means all that could be desired. When 
a small quantity lias to be measured, an error of reading which would have no 
importance in the case of either head breadth or head length, the cephalic index 
being in question, becomes of very great significance in the case of the simotic 
or even the mesodacryal indices. Further in the handling of Merejkowsky's 
instrument, there is much play for personal equation, and only after long practise 
will the recorder settle down into a process, which repeats within reasonable limits 
the values of the indices previously determined. In the next place for our present 
purposes only small series of crania were as a rule available, e.g. 20 to 40 of either 
