THE llED AXD NORWICH CRAGS. 



44^ 



which differs from Lntra vulgaris in having the carnassial tooth 

 longer from heforo backwards, and proportionately narrower, while 

 its inner cusp is smaller than in this recent species. The entire 

 alveolar border is preserved, excepting tliat for the incisors, and 

 measures from the back of the canine to the back of the hindermost 

 molar 40 mm. The depth of jaw below the middle of the carnassial 

 tooth is 17 mm. The carnassial itself is 1 (3 mm. long, 6 mm. wide, 

 and the crown is 5 mm. high. The number of cheek-teeth is appa- 

 rently the same as in L. vahjaris (c. l, pm.~3, m. 2) ; but the front 

 premolar seems to have been smaller and placed more obliquely, 

 while the hinder premolar was larger than in L. vulyaris. The 

 fangs of the premolars also differ from those of L. vulgaris in that 

 each tooth has the hinder fang much larger in proportion to the 

 front one, and this is especially the case in the tooth immediately in 

 front of the carnassial, the piece of fang remaining in the hinder 

 alveolus of this tooth being nearly three times the size of the ante- 

 rior fang. These differences prevent the lled-Crag specimen from 

 being referred to Lutra vulgaris. 



Lutra Valetoni, as figured by 11. Filhol*, shows the alveolar border 

 a little longer than it is in our specimen ; but the carnassial tooth 

 is proportionately smaller : moreover //. Valetoni has four premolars, 

 and these approximately equal in size. 



Lutra afflnis, Gervaisf, seems to have little to distinguish it from 

 L. vulgaris. 



Lutra Bravardi^ Pomel J, corresponds in size with the Red-Crag 

 specimen; but, as the species is onJy represented by an upper jaw, 

 it cannot be compared with our example of a lower jaw. 



Lutra duhia, Blainv.§, from the Pliocene of Sansan, bears a very 

 close resemblance to our specimen ; and I have been able to com- 

 pare it more closely, as Prof. A. Gaudry has kindly sent me a cast 

 of the type, which is preserved in the Museum d'Histoire Naturelle 

 at Paris. The length of the alveolar border is the same in both 

 specimens ; the carnassial teeth are as nearly as possible of the same 

 length ; the premolars have similar large posterior fangs, and 

 decrease in size towards the front in tlie same manner : also the 

 depth of the jaw below the carnassial is the same. The greatest 

 differences observable are — that the Paris specimen has the ramus 

 deeper below the premolars, the carnassial tooth not quite so narrow 

 at its hinder pait, and not so much curved from before backwards. 

 The last molar also seems to be somewhat larger than the tooth 

 could have been which occupied the hinder alveolus of the lled- 

 Crag specimen. These differeiices, which are to some extent due 

 to wearing and rolling, arc not sufficient, as it seems to me, to pre- 

 vent this Eritish Ked-Crag lower jaw being referred to De Blain- 

 ville's Lutra duhia. 



* Ann. Sci. Gcol. vol. x. pi. vii. (1.^79). 



t Zool. Pal. Fr. edit. 2, p. 244 (18.")9). 



\ Gervais, loc. cif. p. 243. 



§ ' Cstcographie,' Genus M/isfr/o., p. "6, pi. xiv. 



