KO. 5 MAMMALS OF PANAMA — GOLDMAN' 1 15 



zygoma, and the broad posterior ends of the prcniaxilla; which arc 

 more nearly conterminous with the nasals; in H. a. lomitcnsis the 

 nasals reach farther posteriorly. 



This pocket mouse was taken mainly under logs in the forest at 

 from 1, 800 to 2,000 feet altitude on the lower slopes of the Pirre 

 Range ; the upper slopes, above 4.500 feet, are inhabited by the very 

 different form, H. desinarestianus crassirostris. 



Specimens examined : Cana, 5. 



HETEROMYS DESMARESTIANUS REPENS Bangs 



Chiriqui Spiny Pocket Mouse 



Hetcromys rcpcns Bangs, Bull. Mus. Comp. Zoo!., Vol. 39, No. 2, p. 45, 

 April, 1902, text fig. 27. Type from Boquete, Chiriqui, Panama (altitude 

 4,000 feet). 



Several apparently well-marked forms of the genus Heteromys, 

 clearly referable to the H. desinarestianus group, have been described 

 from Panama * as distinct species. The alleged species are based on 

 collections from few localities, and while comparison of the various 

 series reveals remarkably constant differences the differential char- 

 acters suggest probable intergradation and the advisability of reduc- 

 ing these forms to subspecific rank. Their evolution, like that of 

 other groups, appears to be largely a result of widely differing 

 environmental conditions within restricted geographic areas. 



The Chiriqui spiny pocket mouse is based on six specimens col- 

 lected by W. W. Brown, Jr., on the southern slope of the lofty 

 Volcan de Chiriqui. It is a dark-colored species similar to H. desina- 

 restianus desinarestianus of Guatemala, but smaller and lacking the 

 orange buffy lateral line of that species ; it differs also in cranial de- 

 tails, the rostrum broadening more gradually to the zygomata, the 

 nasals reaching posteriorly beyond the premaxill.-e, and the molari- 

 form teeth smaller. Closer relationship is shown to H. desinaresti- 

 anus fuscatus of Nicaragua, which is about the same in size, with a 

 more blackish face, and differing in slight cranial details, the nasals 

 and premaxillae being more nearly conterminous posteriorly. 



It is also similar to its nearer geographic neighbors in eastern 

 Panama. From H. desinarestianus zonalis of the Canal Zone it is 

 distinguished externally by the more ochraceous buffy suffusion of 

 the upperparts. The skull differs in the greater posterior develop- 



^ Heteromys fuscatus Allen from Tuma, Nicaragua, may confidently be 

 assigned to the same subspecific series and stand as Heteromys desmarestiartus 

 fuscatus Allen. 



