OCR Text |
Show 4 MR. R. LYDEKKER ON A NEW FOSSIL OTTER. [Jan. 14, as Dr. Schlosser points out, certainly does not belong to that species. With regard to L. franconica, it may be observed that this species was founded on limb-bones, of which the age is unknown, and which may be referable to one of the earlier named species, if indeed it really belongs to Lutra at all. The species represented by the mandible described as L. valetoni, if distinct from all the other forms, requires a new name. The Siwalik jaw, upon the evidence of which I have founded the species L. bathyynathus1, is at once distinguished by the great relative depth of the mandible; while L. palcsindica2, of the same deposits, is a smaller form closely allied to L. sumatrana3. Assuming its distinctness from all recent Otters, there accordingly appears to be good evidence that the Eppelsheim mandible indicates a new species, for which I propose the name of Lutra hessica. In attempting to define this species from the characters of the lower jaw only, I am fully aware how extremely difficult it would be to distinguish the existing species of Otters upon such evidence alone; but since the named fossil forms are very few in number, the objection does not apply so forcibly in this case. If, indeed, we examine the lower jaws of existing Otters, we shall find that it is possible to distinguish a large number of them by the characters of the mandible; some of the most important features being the relative length of the lower carnassial to that of the last premolar, and the proportionate size of the inner cusp of the former tooth. Thus in the large L. brasiliensis the carnassial is comparatively small in proportion to pm. 4 ; in L. ellioti4, (B of woodcut) it is considerably larger; while in L. cinerea (D of woodcut) the proportionate size of the carnassial attains its greatest development. Again, while the inner cusp of the carnassial is very large in L. cinerea, L. paranensis, and Li. brasiliensis, it becomes somewhat smaller in L. vulgaris, and still more so in L. sumatrana, where the entire crown of this tooth becomes very narrow. The carnassial is also narrow^ with a rather smaller inner cusp, in the S. American L. felina. Now L. hessica is an Otter of slightly larger size than the Oriental L. ellioti, but with very similar proportions in the length of the carnassial and pm. 4 ; the inner cusp of the blade of the carnassial is, however, decidedly larger than in the existing form, in which respect it agrees better with the larger L. brasiliensis. The cingulum on the inner side of the carnassial is more distinct than in L. ellioti, and the inner wall of the talon somewhat higher. The dimensions of the lower teeth of the two forms are as follows, in millimetres :- L. hessica. L. ellioti. Length of pm. 4 -f- m. 1 26 24 pm-4 (?) 10 9-5 ni. 1 16 15-5 1 Pal. Ind. ser. 10, vol. ii. pi. xxvii. fig. 3. 2 Op. cit. fig. 2. 3 See Thomas, Proc. Zool. Soc. 1889, p. 193, note 1. 4 I provisionally follow Mr. W . T. Blanford in employing the narnei. ellioti for the Otter in question, since there seems considerable doubt whether Mr. O Thomns's proposal to substitute the name L. barang will meet with acceptation' |