686 CLASS xvn. 



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

 the genus Mesomys WAGN. See J. REINHARDT VidensL Meddelelser fra 

 den naturh. Forening iKjobenhavn, 1849, l %5> PP- IIQ IJ 5> BDRMEISTEB 

 Syst. Uebers. der Thiere Erasiliens, 1854, s. 208, 209. 



Nelomys JOUKDAN, ISID. GEOFFK., Loncher -es WAGN. Characters 

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

 broad. Molar teeth with crown oblong. 



Sp. Loncheres cristatus ILLIG., BURM., Echimys cristatus GEOFFR., DESMAR., 

 Loncheres chrysurw LICHTENST., BUFF. Suppl. vn. PI. 72, (fig. and 

 descr. of ALLEMAND), ISID. GEOFFR. 1.1. PL 21, WATERH. Mamm. n. PL 

 1 7, fig. 2 ; in this large species the tail is hairy ; other species have the tail 

 nearly naked, like mice, as Loncheres armatus WAGN., Mus hispidus LICH- 

 TENST., &c. 



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

 romys villosus DEVILLE, GU^RIN Revue et Magas. de Zool. 1852, PL 15, pp. 

 360, 361. 



Carterodon WATERH. Incisors broad, upper indented on the 



4 4 

 outer part by a longitudinal groove. Molars j -: , 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 incurved, 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 Aulacodus Temminckii. 

 Kongel. Danske Vidensk. Selskdbs Afhandl. ix. 1842, p. 136; WATERHOUSE 

 formed from this a distinct genus Carterodon (Mamm. 11. p. 351), but left 

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

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

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

 delelser, &c. 1851, pp. 23 26. See also BURMEISTER Syst. Uebers. der 

 Thiere Bras. s. 209 211. 



Aulacodus V. SWINDEREN, TEMM. Incisors broad, short, trun- 

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



4 4 



j 2 , complex, upper with three external folds and one internal. 



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



