140 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 97 
of the enamel pattern of a series of spiny rats from Lagunas, eastern 
Peru, which agrees with this species. These Peruvian rats were 
assumed to be representatives of P. semispinosus. 
Specimens examined.—Fourteen (5 males, 9 females, of which only 
7 are adult), a]] specimens in the collection Be the University of Michi- 
gan Museum of Zoology, Nos. 80068-80081, inclusive. 
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O 
