92 MR. E. R. ALSTON ON THE ORDER GLIRES. [Jan. 18, 



nal and internal enamel-folds ; the lower with one external and two 

 internal folds, dividing them into narrow angular lobes. 



C. Echinomyin^e. Grinding-teeth semirooted or rooted, with 

 deep, curved enamel-folds. Fur more or less harsh, often mixed with 

 spines. Tail usually long. Neotropical and Ethiopian. Recent 

 genera : — ■ 



9. Carterodon, Waterhouse, Nat. Hist. Mamm. ii. p. 351 (1848). 

 Muzzle blunt; ears moderate; tail short, clad with scales and rather 



long hairs. Skull broad, with no marked crests ; frontals with deli- 

 cate supraorbital ridges. Incisors broad, with longitudinal furrows 

 and raised ridges. Upper grinding-teeth with one internal and two 

 external enamel-folds ; the lower similar but reversed. 



10. Myopotamus, Geoffroy, Ann. du Mus. vi. p. 81 . . . (1805). 

 Muzzle blunt ; pollex with a truncated nail ; hind feet large, with 



the first four digits fully webbed and the fifth free ; tail moderate, 

 cylindrical, scaly. Skull elongated, with sharp occipital and sagit- 

 tal crests ; auditory bullte small ; paroccipital processes very long. 

 Incisors fiat, plain. Grinding-teeth as in Carterodon, but the lower 

 with three internal folds. 



1 1 . Cercomys, F. Cuvier & Geoffroy, Mammiferes, 6 me livr. ( 1829). 

 Muzzle pointed ; ears rather large ; fur without bristles or spines ; 



pollex very small, with a short nail ; hind feet not webbed ; tail long, 

 scaly. Skull ovate ; frontals contracted, with sharp supraorbital 

 ridges, coronoid process small. Incisors flat. Grinding-teeth with 

 nearly circular crowns; the upper with one internal and three external 

 enamel-folds ; the lower similar but reversed. 



12. Loncheres, Illiger, Prod. Syst. Mamm. p. 90 ... . (1811). 

 Muzzle blunt ; ears rather short ; fur in most species mixed with 



flattened lanceolate spine ; toes subequal ; second digit of fore feet 

 with a broad truncated nail ; tail long, clad with scales and hairs. 

 Skull like that of Cercomys. Incisors narrow. Upper grinding-teeth 

 like those of Cercomys, but longer, with the middle folds usually 

 meeting in the middle ; the lower with one external and two internal 

 folds. 



13. Mesomys, Wagner, Wiegm. Arch. 1845, Th. ii. p. 145 (1845). 

 External characters as in Loncheres ; but pollex with a short 



curved claw, fur without spines, and tail short, thickly haired. No 

 distinct supraorbital ridges. Incisors broad. Upper grinding-teeth 

 with one or two external folds ; the lower similar but reversed. 



14. Echinomys ( = Echimys), Desmarest, Nouv. Diet, d'llist. Nat. 

 x. p. 45 (1817). 



Muzzle pointed ; ears larger than in Loncheres ; feet narrower, the 

 toes more uneven in length, fur usually mixed with spines. Palate 

 shorter and broader. Incisors narrow. Grinding-teeth as in 

 Mesomys. 



