1908.] Allen. Mammals from Nicaragua. 659 



lacking the brown pectoral spot so conspicuous in nudipes; sides paler and much 

 less golden; ventral surface clear white; it is also much smaller with the skull 

 relatively narrower. 



Total length (type), 240 mm.; tail vertebrae, 110. Average of 10 adults from 

 Matagalpa, total length, 235 (220-250); tail, 113 (110-130). Skull (type), occipito- 

 nasal length, 33.5; width of braincase, 13. Six Matagalpa specimens, occipito- 

 nasal length, 32.3 (31-33.5); width of braincase, 13.3 (13-13.5). Ten adult 

 specimens from San Rafael del Norte and Ocotal present the same averages and 

 ranges of variation. (The type is one of the oldest and the largest specimen of the 

 series). 



Compared with a similar number of adults of P. nudipes, the average 

 differences are as follows: Total length, P. nudipes, 260 (255-265); tail 

 vertebra, 126 (120-135); skull, occipitonasal length, 34 (33-35); width 

 of braincase, 14 (13.7-14.3). Thus P. nicaraguce is about an inch shorter, 

 with the tail half an inch shorter, the skull about 2 mm. shorter and nearly 

 a millimeter narrower across the braincase. The ptergoicl fossa in nudipes 

 is conspicuously narrower and relatively longer. 



This species is represented by about 40 specimens, of which 20 are from 

 Matagalpa, 7 from San Rafael del Norte, and several from Ocotal, Volcan 

 de Chinandega, and 13 from Chontales, the latter unfortunately nearly all 

 young. 



36. Mus rattus Linnaeus. Three specimens, all immature. Two 

 are from Matagalpa, Sept. 22, 1907, and one from Lavala, Oct. 12, 1907. 



37. Sciurus boothiae belti Nelson. Six specimens: Matagalpa, 3 

 specimens, Jan. 31, Feb. 1, March 7, 1907; Lavala, 1 specimen, Oct. 18, 

 1907; Chontales, 2 specimens, Feb. 15, 1908. 



In five of the specimens the ventral surface is deep rusty rufous, with 

 small irregular patches of white, either on the breast or abdomen or on both, 

 with a median line of white in one. The other (a female) has the ventral 

 surface much paler yellowish rufous with a small patch of white on 

 the breast, lower abdomen, and in each axilla. 



38. Sciurus griseoflavus (Gray). Six specimens are provisionally 

 referred to this species. They fall into two groups, both geographically 

 and in coloration: Matagalpa, 3 specimens, Sept. 12, 17, and 28, 1907; 

 Volcan de Chinandega, 2 specimens, May 12, 1907; San Rafael del Norte, 

 1 specimen, April 7, 1907. 



In the Matagalpa specimens, the dorsal surface is pale buffy gray in two, 

 varied with black; in the other the black wash is the prevailing color, and 

 the buffy suffusion is much stronger. The ventral surface in two is mainly 

 white, with a lateral band of yellow extending along the lower edge of the 

 flanks from the head to the base of the tail, and including also the inner sur- 

 face of both fore and hind limbs ; in the other the ventral surface (including 



