220 On Four new South -American Mammals. 



Skull low and flattened. Nasals much expanded behind. 

 Posterior lower premolar slightlj smaller than the middle 

 one. 



Dimensions of the type, in skin : — 



Head and body 100 millim. ; tail 53 ; hind foot (moist- 

 ened) 15; ear (above head) (c.) 3. 



Skull: basal length (c.) 25; nasals 12'5x4 5; interorbital 

 breadth 6; breadth of brain-case 11 ; palate length 15; com- 

 bined length of ?M^'^ 5*1. Lower jaw, condyle to tip of 

 incisors 20*5 ; front of canine to back of m^ 12. 



JIab. W. Cundinamarca, in the low-lying hot regions. 



%)e. B.M. 97.7.2.1. 



This species has most resemblance in colour to P. domes- 

 ticus, Wagn., but differs by its much smaller size and 

 smaller ears. From the known species of its own size it is 

 readily distinguishable by its uniform brownish coloration. 



Ichthyomys trichotisy sp. n. 



Size smaller than in the other species. Colour dark 

 Bmoky or slaty grey all over above and below, with the ex- 

 ception of the chest and centre line of the belly, which are 

 white. Ears short and narrow, their conch only standing 

 up about 4 millim. above the crown, thickly clothed with hairs 

 similar in colour and texture to those on the head, and of an 

 equal length to that of the conch itself ; as a result the ears 

 are quite lost among the general fur of the head. Upper 

 surface of hands silvery white, of feet rather more brownish ; 

 hind toes apparently rather less broadly webbed than in the 

 other species, and the pads smaller and more distinctly 

 defined. Tail about as long as the body without the head, 

 well haired, blackish throughout except at the extreme tip, 

 which, as in /. hydrohates and Soderstromi, is white. 



Skull unfortunately too much broken in the only speci- 

 men to be described, and it can only be noted that the 

 incisors, both above and below, are much thinner and 

 narrower transversely and antero-posteriorly, and that the 

 molars are of about the same size and proportions as those 

 of /. hydrohates, or m^ may be a little smaller. 



Dimensions of the type, in skin : — 



Head and body 130 millim.; tail 114; hind foot 28*5; 

 ear, above head, 4. 



Skull : length of upper molar series 4*8, of lower molar 

 series 4'9. Lower jaw, bone only, 13*5 ] to incisor tip 16*3. 



Hab. W. Cundinamarca, in low country near to Magda- 

 lena E,. 



Type. B.M. 97.7.2.2. 



This species resembles /. hydrohates^ and, if really different, 



