ROSS’ SEAL. AZ 
from the normal number and arrangement of incisors in Ommatophoca, I think that, 
however satisfactorily a seal may fall into a certain sub-family in this respect, one is 
bound to ask first whether the number of incisors is a point of such great importance 
as is thus implied, and secondly, whether a special taste in foodstuffs may not have 
led to something like a reversion in the number as well as in the character of the teeth. 
Presumably, the less differentiated types of seal have the greater number of incisors, 
and so presumably the Cystophorinw, having reduced them to a minimum, have 
departed farthest in this respect from the ancestral type. But having done so, it 
would be as easy at any rate, if not easier, for a seal to revert again to the greater 
number of incisors than to make a still greater reduction as in the Cystophorine. 
This seems to me to have been the case with Ommatophoca, and quite a considerable 
number of points can be adduced in which it shows close affinities with Cystophora 
and Macrorhinus, far more than can be adduced to connect it with the Steno- 
rhinchine. 
For example, if we examine the post-canine series we find in Ommatophoca a 
sie: tendency to reduce their number, giving the ea: abundant variations :— 
= p35 255 5-5 = 55 5—5 
P. P.C. 
P.O, 5 PG. pee po ® moe PC a? pc. 2 G0 Cc: ee ae 
In Machrorhinus, also a strong tendency to reduce, P.C. ae 2, PAS -—*, 
Es 0.2 o—, Px 2%, and almost the same extraordinary variability in their number, 
setting to a similar functional worthlessness such as we have seen holds good in 
Ommatophoca, while in Cystophora, though there is no tendency to reduce the number 
of post-canines, the reason is probably to be found in the fact that its food consists not 
wholly of Cephalopods, but also to a considerable extent of some food which necessitates 
a more useful set of molars for purposes of mastication. 
There is therefore upon consideration of the post-canine teeth, good reason for 
thinking Ommatophoca to be more closely related to the Cystophorine than to the 
Stenorhinchine, ae a member of which shows any tendency whatever to vary from the 
normal type P. 0,2 
—?, save Leptonychotes, in which the = aberrant examples dis- 
coverable in about ee skulls, have P.C. : ~~ =, and P. ce 
not a tendency to reduce the cheek ee as in ee but to multiply them. 
Both in the incisors and in the cheek teeth therefore the affinity of Ommatophoca to 
the Cystophorine seems to be upheld. 
If we now turn to other points, and examine the skulls of the species under 
consideration, we find quite as many and as important points in which Ommatophoca 
resembles Cystophora and Macrorhinus, as we find points in which it resembles any 
members of the Stenorhinchine. For example, to quote from Sir William Turner, the 
skull of Ommatophoca approaches that of Cystophora not only in the vertical inclina- 
=? showing, if anything, 
