113 
of Edinburgh, Session 1869-70. 
above the present sea-level. I have compared these bones with the 
corresponding bones in the skeleton of the common seal, and have 
satisfied myself that they belong to animals of different species. I 
have also compared them with the bones of the other clay seals 
already referred to, and am of opinion that the Montrose seal is an 
adult of the same species as the Stratheden, Portobello, and Grange- 
month specimens. Comparing the lower jaw of the Montrose seal 
with that from Grangemouth, depicted on page 110, we find that 
they have the same general form, differing from each other onW 
slightly in size; that the teeth have the same characters, and are 
implanted in the jaw after the same manner. 
If we compare the lower jaw of the adult Montrose clay seal with 
that of an adult Pagopliilus groenlandicus , we find important dif¬ 
ferences in size, which are expressed in the following table, the 
dimensions being taken in straight lines— 
Length from posterior border of condyle 
Clay seal. 
P. groen, 
to socket of canine tooth, 
Vertical diameter of horizontal ramus 
4-2 
5-1 
opposite last molar, .... 
Antero-posterior diameter of ascending ra¬ 
0-8 
1-0 
mus just above the tubercle, at the angle, 
1*1 
16 
Vertical diameter of ascending ramus, 
1-6 
2-4 
On the posterior border of the ascending ramus of the lower jaw 
of P. groenlandicus , a large triangular tubercle projects obliquely 
backwards and inward; in the clay seals, both adult and immature, 
the corresponding tubercle is not triangular, and has the form of an 
elongated almost vertical ridge. The teeth in the adult clay seal 
are set more closely together than in P. groenlandicus , and though 
the cusps in the fossil are considerably worn, yet there is not that 
preponderance of the central cusp over the anterior and posterior 
cusps in the fossil, as in the Greenland seal. The comparison of 
the temporal bones, and of the upper jaw with its teeth, of the 
adult fossil with the Greenland seal also showed important differ¬ 
ences, so that 1 am constrained to give up the idea, at one time 
thought probable, that these seals were of the same species. 
I have now instituted a comparison between the lower jaws of the 
adult clay seal and of the Pagomys foetidus , and find they correspond 
