302 On new Rodents from Western South America. 



Skull : greatest length in middle line 43*3 ; basilar 

 length 38 ; zygomatic breadth 27"7 ; nasals 16 x 6 - 4 ; length 

 of frontal suture 10-2 ; interorbital breadth 9'1 ; breadth 

 across postorbital processes 11*1 ; least posterior breadth 

 across brain-case 17; greatest posterior breadth on meatus 

 27*5 ; palate length from henselion 20'2 ; diastema 12 ; 

 length of upper molar series (crowns) 9*5 ; greatest diameter 

 of anterior tooth (p. 4 ) 1. 



Hab. Tucuman. Altitude 450 m. 



Type. Old male. B.M. no. 0. 7. 9. 14. Original number 

 133! Collected 25th September, 1899, by Signor Luis 

 Dinelli. 



Although geographically nearest to C. mendocinus, Phil., 

 and C.Perrenst, Thos., this Tuco-Tuco is probably most nearly 

 allied to C. talarum, with which it shares the small size and 

 flattened shape of the skull. It differs, however, from that 

 species by its broader skull, especially the broader interorbital 

 region, more open choana?, and much paler coloration. 



Signor Dinelli also obtained at Tucuman an example of the 

 rare armadillo Dasypus vellerosus, Gray, and of the Chilian 

 opossum Marmosa elegans, Waterh., not hitherto known 

 from Argentina. 



Cyclopes* didactylus ida, subsp. n. 

 Geneial colour of the more greyish type characteristic of 

 the typical C. didactylus from Guiana, not yellowish or 

 golden as in the Mexican and Central-American C. d. dor- 

 salis, Gray. Rump, legs, and tail grey, not yellow. Dorsal 

 stripe indistinct, irregular, almost lost in the coarse marblings 

 of the back. Under surface uniform dull yellowish or buffy, 

 without any trace of the dark sternal line present in the other 

 subspecies. 



Skull very like that of the Guianan form ; edges of inter- 

 orbital region similarly evenly diverging backwards. 

 Dimensions of the type, in skin : — 

 Head and body (c.) 180 millim. ; tail (c.) 198. 

 Skull : greatest length 49 ; greatest breadth of brain-case 

 23"5 ; length of nasals (laterally) 13'5 ; interorbital breadth 

 9"6; length of frontal suture 23 - 6, of parietal suture 8 - 7 ; 

 length of lower jaw 33. 



Sab. Oriente of Ecuador. Type from Sarayacu, Upper 

 Pastasa River ; another specimen from the Rio Napo. 



Type. Female. B.M. no. 80. 5. 6. 69. Collected by 

 Mr. Clarence Buckley. Four specimens from Sarayacu 

 examined and one from the Napo. 



* Gray, 1821. Cyclothurus, Gray, 1825, auctorum. 



