Neotropical Mammals. 165 



Dimensions (taken on the skin) : — 



Head and body 2^^ mm. ; tail 86 ; hind foot, s. u. 41, 

 c. u. 45. 



Hab. Campo of Province Sara, near Santa Cruz de la 

 Sierra, Bolivia. 



Type. Adult male. Collected by Mr. J. Steinbach. 



This striking species differs so widely in its coloration 

 from every known Ctenomys tliat even in the absence of the 

 skull I have no hesitation in describing it as new. Its colour 

 above is extraordinarily like that of Zygogeomys trichopus 

 and some other Geomyidaj, which have a similar coppery- 

 brown tone, while all the hitherto known Ctenomys are of 

 some fawn or buffy tint. 



A baby specimen of Ct. Steinhachi, only 100 mm. iu 

 length, is of precisely the same colour as the adult. 



TJie Local Forms o/ Dasypus sexcinctus, Linn. 



While the extreme forms of the Dasypus sexcinctus group 

 are, as shown in a former paper *, so widely ditferent in size 

 that it seems impossible for them to belong to the same 

 species, further material from intermediate localities tends to 

 fill up the gap between them, and I am now disposed to 

 regard them as forming but a single species with several 

 geographical races. 



These races may be briefly distinguished as follows : — 



1. Size smallest ; greatest skull-leugtli 95 mm., 



cephalic shield in an average specimen 



87x05. Colour brown. About 31-33 



scales in movable bands. Back thinly 



haired, the pelvic shield practically naked. [Linn. 



(Para.) 1). sexcinctus sexcinctus, 



2. Size medium ; greatest skull-length of adult 



111 mm., cephalic shield about 103x77. 

 Colour paler, more yellow. Hairs as in 

 sexciiictus. (Bahia.) D. s, setosns, Wied. 



3. Size largest ; greatest skull-length attaining 



126 mm,, cephalic shield 123 x 88. Colour 

 brown. Hairs as in sexcinctus. (Matto 

 Grosso, Paraguay, and South Brazil.) .... D. s. (/ilvijics, 111. 



4. Size rather less than in gilvipes ; cephalic 



shield 114x89 mm. Colour pale horny. 

 Movable bands with 36 scales. Back 

 scantily haired. Skull short and broad ; 

 molars broad and rounded. (Bolivia.). ... D. s. bvlivicc, subsp. n. 



5. Size as in botivice ; cephalic shield 116x78 



mm. Colour sandy. 36 scales in movable 



bands. Back well haired, the pelvic shield 



with many white hairs. Nasals rather [subsp. u. 



pecidiar iu shape. (Tucuman.) D. s. tucumanus, 



* P. Z. S. 1903, ii. p. 242. 



