30 EDWARD A. WILSON. 
There appears to be a good deal of individual variation in the extent and distri- 
bution of the pigmentation in the hair of Stenorhinchus. The four skins in the 
‘Discovery’ and ‘Morning’ collections, although having in each case the main 
distinctive character, are strikingly different in this respect. No. 66, for example, is 
an exceedingly handsome skin, richly marked with jet black and dark grey, particularly 
upon the throat, shoulders, flanks and hind flippers. These are the usual areas upon 
which the dark markings appear, or, rather, one should say remain ; for the character 
of the marking in all of the Antarctic seals is such that one may more easily consider 
it brought about by the greater or lesser confluence of white spots upon a dark 
ground. This is the case even in Lobodon, where the white spots are confluent to such 
an extent that in many cases no trace of the ground colour is left. This is the case 
also, and to a considerable extent, in Stenorhinchus and Leptonychotes. It is less 
apparent in Ommatophoca. The result of the partial confluence of white spots in 
young examples of Lobodon, and in all examples of Stenorhinchus, is that rings, more 
or less complete, of pigmented hair remain to form the characteristic dappling on 
certain areas, these being constant in each case. The first part of the body to be wholly 
whitened is the abdomen and the throat, the last the back and dorsal aspects of the 
limbs and sides of the head. In No. 66 the pigmentation is much in excess of the 
average, so that there are even black markings remaining on the abdomen, and the 
throat is very richly marked. For descriptive purposes, the skin of Stenorhinchus may 
be conveniently divided into a dorsal, a ventral and an intermediate lateral area. The 
first is dark grey with black markings, the second is pale with no marking as a 
rule, the third is grey, freely spotted with both black and white. Specimen No. 65 
is a richly marked skin, but of a different type to No. 66. The dorsal area is dark 
grey but with multitudinous and small black markings, the lateral area freely spotted 
with white and black, and the ventral area, particularly the throat, but slightly 
marked with black. No. 18 is again a third type, with few and indistinct markings, 
being of a rather dirty grey colour dorsally and ventrally, and only a pale grey below ; 
yet there is no doubt, even in this poorly-marked skin, that the distribution and 
appearance of the darker markings is characteristic of Stenorhinchus. 
It is a significant fact that in the ten skulls of Stenorhinchus now in the British 
Museum, there is to be found no variation at all in respect of the number, either of the 
incisors or of the cheek teeth. In each case the formula is strictly Stenorhinchine, 
2—2 .1—1 5—-5 
ee 
This uniformity in a species of the true seals is quite unusual. Lobodon car- 
cinophagus, Phoca greenlandica, and Stenorhinchus leptonyx are the only species in 
which I have been unable to discover aberrant dental formule. This point is 
obviously connected with efficiency from a functional point of view, for the teeth are 
strong and well adapted to the food upon which their owners live, although they are 
in each case also highly specialised in form. 
