OCR Text |
Show 1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 383 its fore cusp much smaller, the Hyaena's being larger relatively in Felis. The relative proportions of the mid and hind cusps in Gulo are much as in Hyana. The internal cusp is not so big relatively as it is in Hyana, though it is more like that of Hyana than that of Felis. The first molar is a little larger than in Hyana, which is intermediate between Gulo and Felis as regards the development of this tooth. In the lower jaw the fourth premolar is less trilobed and the principal lobe is less developed. The sectorial has a large heel. There is a second true molar. Gulo compared with Cryptoprocta, Hyaena, and Felis.-In the upper jaw the third premolar of Cryptoprocta is intermediate in form between that of Felis and that of Gulo, but is more like that of the former. The same is the case as regards the upper sectorial, both as regards the three external cusps and the inner cusp. The first upper molar of Cryptoprocta is also intermediate in its development, but is much more Cat-like than Glutton-like. In the lower jaw the canine of Cryptoprocta is more like that of Felis than is the case with the canine of Hyana. The fourth premolar has a less trilobed crown in Gulo than in Cryptoprocta. The sectorial has a small heel, but not like that of Gulo, and the last genus alone of the three has a second true molar. Gulo compared with Canis.-In the upper jaw the third premolar is smaller, and has a smaller posterior cusp. The sectorial is very-like that of Canis, but the hindmost cusp is rather thicker transversely. Gulo has a much smaller first true molar and no second one. In the lower jaw, the fourth premolar is less trilobed, or rather less quadricuspidate, this tooth of the Dog being much like that of the Hyaena. The sectorial of Gulo has a smaller heel and the mid cusp predominates less over the fore cusp. The second true molar is much smaller and there is no third molar. The brain * shows an elongated Ursine lozenge. The cerebrum is very wide posteriorly and its dorsal surface is much complicated, the anterior limb of the sagittal gyrus being greatly expanded and convoluted, while posteriorly it is medianly grooved. Lutra2.-The Otters, of which there are at least nine, possibly a dozen species (of very uniform coloration), are found over all the geographical regions except the Australian. No species, however, appears to be common to the Old and New Worlds. It is therefore the most cosmopolitan genus of Arctoids we have yet met with. The external characters of the genus are familiar, but it may be noted that the muzzle has no central groove or only a trace of it at 1 See I. c. p. 17. 2 Erxleben, Syst. n. 448 ; Schreb. Saug. in. p. 457, pi. 126 a ; Desm. M a m m. p. 188; Bell, Brit. Quad. p. 129; Buffon, Hist. Nat. vii. p. 134, pi. 11-17; Wagner's Supp. ii. p. 249; P. Gervais, M a m m . ii. p. 116; Gray, P.Z.S. 1865, p. 126 ; Cat, Carnivora B. Mus. p 100; De Blainville, Osteog. Mustela ; Linn'. S. N.'i. p. 66 (Mustela lutra); Pallas, Zoogr. i. p. 76 (Viverra lutra). Under this genus are also included Gray's genera Barangia, Lontra, Nutria, Latronectes. Hudroqale, Latax, Pteronura. See Cat. Carnivora of Brit. Mus. pp. 100-113. |