i68 FIELD MUSEUM or NATURAL HISTORY ZOOLOGY, VOL. X. 



ready at the least alarm to spring back into cover. I saw several in 

 such places quite reminding of rabbits in a northern country. 



Proechimys brevicauda (Giinther). HUALLAGA SPINY RAT. 



Thirty- two specimens, vicinity of Yurimaguas. 



This series includes specimens of varying ages from those in the soft 

 sooty juvenal coat to very aged ones with harsh pelage and teeth worn 

 down nearly to the roots. In spite of a color variation, which within 

 its limits ranges freely, the series as a whole presents a general appear- 

 ance of uniformity. The greatest variation is in the under parts which 

 can scarcely be said to be exactly alike in any two individuals. Fulvous 

 and white are distributed in varying proportions, in general occupying 

 about equal areas of the under parts. The chin and throat with scarcely 

 any exception are fulvous and likewise the sides of the belly. Some- 

 times the white is reduced to a small pectoral and an inguinal patch or 

 it may cover practically the entire belly and run forward to the middle 

 of the throat. 



Chamicuros, the type locality of brevicauda, is not far from Yuri- 

 maguas, and as was to be expected, Giinther's type shows practically 

 complete agreement with our specimens, comparison with which has been 

 made by Mr. Thomas. Average flesh measurements of seven adults 

 are as follows: Total length 372* (335-420); head and body 230 (205- 

 277); tail 141 (130-162); hind foot 49 (46-52). 



Mr. Anderson found these rats abundant in the vicinity of Yurimag- 

 uas especially in small chacras where they were feeding on plantains. 



Proechimys sp. SPINY RAT. 



Thirteen specimens, Lagunas, Huallaga River. 



Although agreeing in size and general cranial characters with P. 

 brevicauda, this series as a whole is so markedly different in color that 

 at first glance its distinctness would scarcely be doubted. The general 

 appearance is much the same as that of P. semispinosus, the under parts 

 being in every case pure snowy white throughout without any trace of 

 the fulvous so characteristic of brevicauda. There is also a soft quality 

 in the pelage which is not shown by the Yurimaguas series of brevicauda. 

 When specimens from many more localities are available, it seems 

 probable that a fulvous-bellied and a white-bellied form may be differ- 

 entiated and some definite range be assigned to each. To attempt to 

 do this now would serve no particular purpose and might cause future 

 confusion. 



