686 CLASS XVII. 



beino- caused probably by the sand-fleas (Pulex penetrans), have occasioned 

 the genus Mesomys Wagn. See J. Eeinhaedt Vidensl: Meddelelser fra 

 den naturh. Forening i Kjobenhavn, 1849, 1850, pp. no — 115, Buemeister 

 Syst. Uehers. der Thiere Brasiliens, 1854, s. 208, 209. 



Nelomys Jourdan, Isid. Geoffr., Loncheres Wagn. Characters 

 of the genus. Ears moderate, rounded. Tarsi somewhat short, 

 broad. Molar teeth with crown oblong. 



Sp. Loncheres cristatus Illig., Borm., Echlmys crisfatus G-eoefr., Desmae., 

 Loncheres chrysuriis Lichtenst., Buff. Snppl. vii. PI. 72, (fig. and 

 descr. of Allemand), Isid. Geoffe. 1.1. PI. 21, Wateeh. Mamm. 11. PI. 

 17, fig. 2 ; in this large species the tail is hairy; other species have the tail 

 nearly naked, like mice, as Loncheres annatus Wagn., Mus hispidm Lich- 

 tenst., &c. 



Some species have no spines. Such a species with a hairy tail is Lasiu- 

 romys villosiijS Deville, Gueein Revue et Magas. de Zool. 1852, PI. 15, pp. 

 360, 361. 



Carterodon Waterh. Incisors broad, upper indented on the 



4-4 



outer part by a longitudinal groove. Molars . _ . , complex, 



crown quadrate and rounded, the upper with one internal and two 

 external folds of enamel, the lower with one external fold and two 

 internal. Ears small, rounded. Thumb-wart of fore feet with nail 

 flat ; the other claws incm'ved, concealed by rigid hair. Narrow 

 spines, terminating in a very fine point, intermixed with hair. 

 Tail hairy, moderate. 



Many years ago skulls of a rodent with grooved incisors were found by 

 Lund in caves of Brasil, which he referred to a species of Echinomys, and 

 first named Echinomys sulcidens, but afterwards Aulacodm TemmlncUi. 

 Kongel. DansTce VidensTc. SelsJcabs Afhandl. ix. 1842, p. 136; Waterhouse 

 formed from this a distinct genus Carterodon {Mamm. il. p. 351), but left 

 it undetermined whether or no the animal was fossil only. At length 

 J. Eeinhaedt obtained two living specimens of this animal, which he 

 described in 1851 under the name of Carterodon sulcidens, Yidensh. Med- 

 delelser, &c. 185 1, pp. 23 — 26. See also Buemeister Syst. Uehers. der 

 TJdere Bras. s. 209—2 1 1 . 



Aulacodus V. Swinderen, Temm. Incisors broad, short, trun- 

 cated, straight, brown in front, the upper trisulcate. Molar teeth 



"~ , complex, upper with three external folds and one internal. 



Ears somewhat short, rounded. Fore feet with thumb and outer 



