1893-] Allen and Chapman on Trinidad Mammals. 219 



encloses the middle portion of the fore arm and a short space on the leg at and 

 just above the ankle. Upper surface of all the feet white. Palms flesh-color, 

 soles blackish, both entirely naked. Ears large, for a member of this genus, 

 flesh-colored at the base, passing into blackish apically, which is the color of 

 most of the exposed portion. Tail considerably longer than the body, sharply 

 bicolor, dusky above and whitish below, naked and nearly tuftless at the end, 

 the very short hairs scarcely at all concealing the annulations. 



The pelage of the dorsal surface consists largely of grooved spines, almost 

 wholly so over the greater part of the back, mixed sparingly with fine bristly 

 hairs ; on the sides of the body the spines are weaker and fewer, here, as below 

 and on the head, the pelage consisting of rather coarse stiff hairs more or less 

 profusely mixed with softer hairs. The whole *pelage above, spines as well as 

 hairs, is whitish basally, passing into blackish and tipped generally with very 

 pale bay or chestnut. The flanks and limbs, however, are rather paler and 

 grayer than the middle region of the back. 



Measurements. The average and extreme measurements of ten fully adults, 

 taken in the flesh, are as follows : Total length, 280 (265-292) mm. ; head and 

 body, 130 (120-142); tail, 150 (135-160); hind foot, 33 (31-35); ear from 

 crown, 14.5 (14-16). 



An average adult skull measures as follows : Greatest length, 36 ; basal length, 

 28 ; greatest zygomatic breadth, 26 ; least interorbital breadth, 13.5 ; distance 

 between incisors and first molar, 9.5 ; crown surface of upper molar series, 4.5 ; 

 lower jaw, length, 20 ; height at condyle, 12.5. 



Young. Nursing to half or two-thirds grown young are dusky plumbeous 

 with a slight sooty tinge, but otherwise marked as in the adult. At a more 

 advanced stage the general color becomes a little lighter or grayer, with a faint 

 tinge of brown. The hair on the middle of the back becomes coarser and 

 stiffer, but well-developed spines do not appear much before the animal attains 

 adult size. 



The only other species of this genus available for comparison 

 with the present is Hcretomys alleni, of which the Museum has 

 now a large series, collected in the vicinity of Brownsville, Texas. 

 This proves so distinct from H. anomalus that no comparison 

 between the two is necessary, except that it seems desirable to 

 improve the present opportunity to elucidate further the charac- 

 ters of H. alleni? The youngest specimen (about half-grown) 

 of H. alleni indicates that the young, even during the suckling 

 stage, are not greatly different in general coloration from the 

 adults, being perhaps a little paler and more uniform gray, and 



See this Bulletin, III, No. 2, pp. 268-272, June, 1890. 



