188 BULLETIN OF THE 



dark color of the fore leg is separated from that of the upper parts by the fawn- 

 colored stripe ; that of the hind leg is continuous. Ears conspicuously bor- 

 dered with white. The general color of the upper parts is blackish intimately 

 grizzled with gray and sandy ; the dark colors predominate and give the gen- 

 eral effect on the back, the admixture of sandy increasing on the sides in 

 approaching the fawn-colored stripe. The spines are colorless in all their 

 grooved portion, the smooth sharp lips being blackish ; these comprise one fifth 

 to one fourth of the whole length. The very slender hairs intermixed with the 

 spines are similarly colored. The spines are restricted to the upper parts ; 

 elsewhere the fur is soft, but coarse, and there appears to be no under fur. The 

 hairs of the white under parts, and of the fawn-colored stripe, are uniformly 

 colored from root to tip. The tail sharply bicolor, blackish above and white 

 below, fully haired, the hair completely hiding the scales ; the pencil at the 

 end is entirely dark-colored and occupies the terminal inch of the vertebrae. 

 Whiskers partly blackish and partly colorless. Claws nearly colorless. Inci- 

 sors yellow. 



" The length of the well-prepared skin (No. 5889, M. C. Z.) is 4.30 inches. 

 Tail vertebrae the same. Tail with hairs, 4.V5. Hind foot, 1.15. Ear, .55 

 above notch. 



" As above stated, this example is of the size of Perognathus fasciatus, which 

 it much resembles in general appearance, especially in the conspicuous fawn- 

 colored stripe along the sides ; in its long tufted tail it resembles P. pencillatus, 

 but is of course generically different from either. The white rim of the ears is 

 also a strong mark." Coues, MS. 



In 1868, Dr. J. E. Gray (Proc. Zool. Soc., 1868, pp. 204, 205) described three 

 species of Heteromys from Mexico (H. longicaudatus,irroratus, and albolimbatus) 

 and one from Honduras (H. melanoleucus), all of which Mr. Alston has re- 

 ferred to a single species, together with another (H. adspersus) from Panama 

 described by Dr. Peters, in each case from an examination of the types. For 

 this species he adopts the name longicaudatus as " the only one of Gray's names 

 which is not absolutely misleading." In view of this large number of syno- 

 nyms it seems presumptuous to take the risk of adding another, although the 

 present example does not agree with the characters given by Mr. Alston for 

 H. longicaudatus, nor with those of any of the species described by Gray, 

 although recalling certain features of two of them. It has, for instance, the 

 white-rimmed ears of H. albolimbatus, and " the yellow streak on the side," or 

 " widish interrupted yellow line," of H. irroratus (which, however, Mr. Al- 

 ston says, is merely " a slight tinge of pale fawn along the edge of the darker 

 coloring "), except that in the present example it is not interrupted and forms a 

 conspicuous feature of the coloration. There is no allusion in any of the de- 

 scriptions, nor in Mr. Alston's diagnosis and remarks, to the conspicuous crest 

 of long (.50 to .65 of an inch in length) blackish hairs along the terminal fifth 

 of the tail-vertebrse, unless it be that the phrase, " short black hairs, which 

 are more abundant on the upper part near and at the tip, forming a kind of 

 pencil," in the description of H. albolimbatus, can be so construed. From Mr. 



