271 



pl. ii. (under the name of Didelphis) ; and also by Owen 

 in the ' Trans. Geol. Soc.' ser. 2, vol. vi. pl. vi. fig. 2, in 

 his ' Odontography,' pl. xcix. fig. 4, and also in his 

 ' Mesozoic Mammalia ' (Mon. Pal. Soc.), pl. i. figs. 26, 26. 

 Presented by W. J. Broderip, Esq. 



Genus AMPHILESTES, Owen '. 



Distinguished from Phascolofherium by the larger number of 

 lower cheek-teeth, and by at least some of the premolars being 

 simpler than the true molars; in the type species (fig. 41) the 

 cingulum of the tricuspidate true molars encircles the crown, and 

 has minute fore-and-aft cusps ; the mandibular condyle is 

 apparently sessile and placed on the level of the molars. In the 

 type specimen 2 (fig. 41) there are nine teeth remaining (the crown 



Fig. 41. 



Amphilestes brodcripi, Owen. Be versed inner view of the left ramus of the 

 mandible; from the Stonesfield Slate. ?. The restoration of the anterior 

 teeth is conjectural ; and the condyle is placed too high. (From Owen's 

 ' Palaeontology ' 3 .) 



of the sixth from the posterior end broken off), of which the first two 

 are clearly premolars ; the third tooth may possibly be a milk-molar, 

 and it is not certain that there may not be an additional molar in 

 its alveolus behind the ninth tooth. 



1 Encyclopaedia Britannica, 8th ed. vol. xvii. p. 157 (1859). In his ' Meso- 

 zoic Mammalia ' (Mon. Pal. Soc.) Owen provisionally included the type species 

 in Amphitherium, but the observations of Osborn (kindly communicated in MS. 

 to the writer) apparently indicate its right to distinction. 



2 Compare Owen's ' Odoutography,' pl. xcix. fig. 3. Owen regarded the 

 lower dental formula as I. r y 0. j, Pm. -, M. - ; but it is quite probable that 

 there may have been four incisors, which would reduce the premolars to five ; 

 while, if the specimen be adult, the seventh tooth from the end might be a true 

 molar, in which case there would be only four premolars ; and there may have 

 been a diastema behind the canine. 



3 Wrongly given in that work (fig. 112) and in the ' Encyclopaedia Britannica,' 

 op. cit., as Amphitherium prevosti, and so reproduced in several later works; 

 it is really reduced from pl. vi. of the ' Trans. Geol. Soc.' ser. 2, vol. vi. pl. vi. 

 fig. 1, and pl. xcix. fig. 3 of Owen's ' Odontography.' 



