1900.] Allen, On Mammals Collected in Southeastern Peru. 221 



32 ; mastoid width, ; interorbital width, 17 ; length of nasals, 17 ; width 



of nasals in front, 6.5 ; distance from nasals to fronto-parietal suture, 19.5 ; 

 diastema, 12.5 ; palatal length, 17 ; upper toothrow, 16 ; lower toothrow, 16.5 ; 

 lower jaw from tip of incisors to posterior border of condylar portion, 41.3 ; 

 height at condyle, 15. 



Dactylomys peruanus is based on a single female, with the teeth 

 well worn, showing it to be fully adult. In respect to its capture 

 the collector states (MS. notes) : " I was looking after my traps 

 just after daylight when I noticed this specimen running along 

 the water's edge of the creek. 1 had no trouble killing it with a 

 stick. Its stomach was filled with the inside of a palmetto nut, 

 or some white tender root." 



The only previously recognized species of the genus Dactylomys 

 is D. dactylinus (Desmarest, 1817, ex E. Geoffrey MS.), based on 

 a specimen in the Paris Museum, received from the Museum at 

 Lisbon, and supposed to have been brought from Brazil. 1 A 

 second specimen, a male, was collected by Natterer, on the Rio 

 Negro ; two specimens, a male and a female, were obtained on 

 Castelnau's Voyage near Sarayacu, on the pampas of northeastern 

 Peru (cf. Deville, Rev. et Mag. de Zool., 1852, 357) ; Dr. Giinther 

 records (P. Z. S., 1876, 743) the reception at the British Museum 

 of " two fine skins of this rare Rodent, unfortunately without 

 skulls, from the Rio Napo," concerning which he gives no further 

 particulars ; and Dr. Jentink mentions (Notes from the Leyden 

 Museum, IX, 1887, 224) the acquisition by the Leyden Museum 

 of an adult male, skin and skull, from the neighborhood of 

 Nauta, opposite the mouth of the Ucayali River, " in north- 

 eastern Peru or Ecuador." Dr. Jentink gives external measure- 

 ments and measurements of the skull of his specimen, but says 

 nothing about its coloration. Neither can I find that the Nat- 

 terer specimen has been described, beyond a transcript of 

 Natterer's field notes by Dr. Pelzeln (Brasilische Saugethiere, 

 1883, 65), giving a few measurements and the color of the naked 

 parts in life. 



The original type specimen of the species has been repeatedly 

 described, by various authors, and its skull and dentition figured 

 (cf. Desmarest, I. Geoffrey, Waterhouse, etc.). Judging from 

 these descriptions D. peruanus is very much smaller than D. 



" Patrie : 1'Amerique meridionale ; probablement Brazil." I. Geoffrey, Mag. de Zool., 

 1840, Mamm., p. 48. 



