IHERIDOMYID^. 237 



27760. Three fragments of the mandible ; from the Lower Miocene 

 of Sauvetat. Oroizet Collection. Purchased, 1848. 



27636. Part of the left ramus of the mandible, showing the first 

 three cheek-teeth and the complete incisor; from the 

 Lower Miocene of Sauvetat. 



Croizet Collection. Purchased, 1848. 



34944-5. Fragments of the cranium and mandible ; from the Lower 

 Miocene of Antoiu. 



Bravard Collection. Purchased, 1852. 



Theridomys aquatilis, Aymard 1 . 

 Syn. Theridomys jourdani, Aym. (non Gieb.). 

 Isoptychus jourdani, Pomel 2 . 

 Isoptychus aquatilis, Pomel 3 . 

 P Theridomys rotundidens, Schlosser 4 . 

 ? Theridomys cuvieri, Pomel. 



This species is considerably smaller than the last, the average 

 length of the space occupied by the upper cheek-teeth being 0,008, 

 and that by the lower 0,010. The four cheek-teeth are nearly equal 

 in size, and there are only three distinct enamel-islands on the worn 

 crowns of the upper teeth. 



Hob. Europe. 



27756. The palatal portion of the cranium, showing the left incisor 

 and the four cheek-teeth of either side ; from the Lower 

 Miocene of Cournon (Puy-de-D6me), France. This spe- 

 cimen agrees precisely with the one figured by P. Gervais 

 in the Zool. et Pal. Franchises, 2nd ed. pi. xlvi. figs. 7, 

 7 a, and by Filhol in the Ann. Sci. Geol. vol. xii. pi. vi. 

 fig. 12. The length of the space occupied by the four 

 cheek-teeth is 0,009. 



Croizet Collection. Purchased, 1848. 



27756 a. The nearly complete left ramus of the mandible, containing 

 the incisor and the four cheek-teeth ; from the Lower 

 Miocene of Cournon. This specimen agrees very closely 

 with the mandibles figured by P. Gervais (op. cit. fig. 6) 

 and Filhol (op. cit. fig. 14). The length of the space 

 occupied by the four cheek-teeth is 0,010. 



Croizet Collection. Purchased, 1848. 



1 Ann. Soc. Agric. Sci. le Puy, vol. v. p. 82 (1850), teste Filhol. 



2 Catalogue Methodique, p. 35 (1853). This species is identified with aqua- 

 tilis on the authority of Filhol, Ann. Sci. Ge"ol. vol. xii. art. 3, pp. 14, 16. 



3 Ibid. * Paleeontographica, vol. xxxi. p. 38 (1884). 



