120 On Mammals from near Tinogasta, Catamarca. 



Frontal region flat. Interparietal perceptible in all specimens, 

 even in the type, which is old enough to have its basilar 

 suture partially closed. Line of posterior ridges directly 

 transverse. Outer base of anteorbital foramen very slender. 

 Malar ridges particularly strongly marked, sharp, the surface 

 concave below them. Meatal area, as viewed from above, 

 apparently larger than usual. A well-marked bulla-island 

 visible on top of skull. Opening of choame not very sharply 

 angular, level with the middle of m 2 . Bullae large and 

 swollen, larger than in knighti and nearly as large as in 

 luteolus, both of these being larger species. 



Molars small in comparison with the size of the animal. 

 Longer diameter of m 3 scarcely greater than shorter. 

 Dimensions of the type : — 



Head and body 205 mm. ; tail 97 ; hind foot 36-5. 

 Skull : greatest median length 47 ; gnathion to back of 

 bulla 49; condylo-incisive length 47 - 5; zygomatic breadth 31; 

 nasals 17'5x8*3; interorbital breadth 93 ; least breadth 

 across brain-case 18 ; bi-meatal breadth 31 ; palatilar length 

 21*7 ; diagonal horizontal length of bulla 18'5, breadth of 

 bulla at right angles to last, exclusive of meatal tube, 9'5 ; 

 upper molar series (crowns) 8'8, oblique diameter of m 1 3'<>, 

 of m 3 1*7. 



Tt/pe. Fully adult male. B.M. no. 20. 5. 11. 39. Original 

 number 891. Collected 17th January, 1920. 



This tuco-tuco is readily recognizable by its uniform pale 

 colour, comparatively long tail, narrow skull, large bullae, 

 and the other characters above detailed. As usual in 

 CttnomySy there appear to be no characters indicative of any 

 group-relationship, but of the two species geographically 

 nearest to it, C. knighti of Otro Cerro is much darker in 

 colour, with shorter tail, broader frontal region, and larger 

 teeth, while C.fochi of Chumbicha is little more than half its 

 bulk, besides differing in other respects. 



Sr. Budin found what he believed to be evidence that these 

 tuco-tucos had cannibal propensities, and devoured the dead 

 bodies of such of their comrades as were caught in the traps. 

 This habit is common in Murida?, but I think had not been 

 before observed in Octodontidse. 



8. Caviella nuenas, Thos. 



S . 844, 852, 860 ; ? . 832, 847, 855, 8G3, 864, 868, 871, 

 881, 882, 888. 



