102 MR. O. THOMAS ON RODENTS FROM PERU. [Jail. 17, 



quil Rat as Nectomys apicalis, g. and sp. n., the genus being founded 

 on the presence of short webs to the toes, including H. sqnamipes, 

 Bts., from which N. apicalis was separated on account of its only 

 having 5 instead of 6 hind-foot pads. I do not, however, think 

 that the presence of webs to the feet is a character of generic im- 

 portance, and should prefer to regard Nectomys as only a subgenus 

 of Holochilus. The specific distinction of H. apicalis is, no doubt, 

 quite correct, as all tlie specimens in the present collection agree in 

 having only 5 hind-foot pads. None of them have, however, the white 

 tip to the tail described by Prof. Peters ; but this is no doubt a point 

 in which there may be considerable variation. The incisors of H. 

 apicalis were originally said to be snow-white ; but the present speci- 

 mens do not agree with this, their incisors being pale yellow ; but 

 they are certainly very much lighter-coloured than in H. squamipes, 

 where they are a rich orange. Notwithstanding these differences, I 

 do not think there can be any doubt that these specimens belong to 

 Prof. Peters's species, as they agree perfectly in size, locality, and 

 the very important character of the number of the foot-pads. 



There is in the British Museum another specimen of this species, 

 collected by Mr. J. K. Salmon at Concordia, Medellin, U. S. of 

 Colombia. 



(a) " Appeared to be aquatic, although caught in a cultivated 

 field." 



(6) " Killed in an arm of the river just as it was seizing a branch 

 of a Guava-tree, which touched the surface of the water. It had in 

 its stomach an aromatic mass composed of fruity substance. It swims 

 perfectly, only coming out late in the evening, and is probably the 

 animal which gnaws the fish taken in the Indians' nets. It is not 

 possible to catch it in a rat-trap." 



4. Hesperomys (Calomys) laticeps, Lund, Blik p. Bras. 

 Dyrev. iii. p. 279 (1841). 



a-c. Huambo, 3700', April and May 1880. 



To this species I refer three specimens, of which, however, only 

 one is adult. The tarsus seems to be somewhat longer than in the 

 original specimens ; but otherwise it agrees very fairly with a spe- 

 cimen of H. laticeps in the Museum collection from the original 

 locality, Bahia. This Bahian specimen, however, is only a skin ; and 

 it is therefore quite possible that spirit-specimens would show such 

 differences from the Peruvian one, that, combined with the greater 

 length of the tarsus and the difference in locality, a new species 

 would have to be formed for the latter. 



The following is a description of the adult individual, a male: — 

 Fur rather short and close, compared with that of H. albigularis 

 or leucodactylus. General colour above dull brown, very finely 



