﻿46 



NORTH AMERICAN FAUNA. 



[No. 12. 



Essential cli a racier s : 



Palate abnormal. 



m 3 Avitliout closed triangles. 



m 1 "with triangles frequently open and 8 or 9 salient angles, 

 m 3 witli triangles usually open and 6 salient angles. 

 Mamma? (number not known). 

 Plantar tubercles, 5. 

 Sole hairy. 



Claws on bind feet longest. 



Fur api^arently somewhat modified. 



81:1111. — 111 tlie Specimens of Eotlienomys tliat I have examiiied the 

 skull is not in sufficiently good condition to permit of any detailed 

 description. The peculiar structure of the bony palate taken in con- 

 nection with the teeth is, however, of itself enough to characterize the 

 group. 



Bony palate. — Unfortunately in the two specimens of 2Ucrotus melano- 

 (jastcr that I have seen (82.6.16.11 and 92.10.12.5, British Museum 

 Eegister) the basal part of the skull is so injured that the form of the 

 interpterygoid fossa can not be determined. 

 The bony palate, however, is sufficiently pre- 

 served to ^ show the essential details of its 

 structure (PI. II, fig. 11). That part of the pal- 

 ate which lies in the level of the roof of the 

 Fig. 22— Enamel pattern of mouth cuds abruptly oppositc the frout cud of 

 r!L;:;;';,a^^::;" .It; back upper molar in a straight-edged shelf 

 which extends without notch or x)rojection from 

 alveolus to alveolus. Although the form is thus strikingly different 

 from that of the typical microtine palate, the vestiges of the structure 

 there j)resent may still be recognized. The lateral grooves and median 

 ridge are present, though slightly developed. The former terminate in 

 two depressions lying just in front of the wide, flat, lateral bridges 

 which completely obliterate the posterior ends of the grooves, and 

 together with the terminal x)art of the median ridge form the edge of 

 the palatal shelf. The palate in all its essential characters is thus 

 exactly like that of Evotomi/s. 



Enamel pattern in general. — The enamel pattern in Eotlienomys (fig. 

 22) is in many ways remarkable. The triangles in all the teeth tend to 

 remain open, the i^oints of the salient angles are blunt and rounded as 

 in Erotomys, the triangles on the outer and inner sides of the teeth are 

 subequal in size, and the maxillary teeth are especially noticeable for 

 their likeness to each other. The figures x)ublished by Blanford^ fail 

 to do justice to the teeth of this species. These are better represented 

 in Milue-Edwards's original plate, ^ in which there is also a hint at the 

 palate structure. 



ijourn. Asiatic Soc. Bengal, L, pt. II, PI. II, fig. A. 



^Eecherches p. servir a I'histoire nat. d. Mammiferes, Vol. I, PI. XL VI, figs. Ic 

 and Id. 



