Dr. J. E. Gray on Rats. 417 



of the orbit, and the concavity on the side of the nose before it. 

 The concavity on the side of the nose in front of the eye is 

 broad and deep, and is suddenly narrowed on the lower side, 

 so as to leave a narrow erect opening on the lower part of the 

 side of the nose, which has a rather raised front edge on its 

 lower part, as in Mus decumanus. 



Fig. 1. 



-Skull of Neomys [mnamensis, 



Neomys panamensis. (Fig. 1.) 

 Mouse-coloured ; back blackisli-washed, with longer hairs ; 

 sides of the head and body rather paler ; throat, chest, und(>r- 

 side of body, and inside of legs white; feet brownish, with 

 white hairs over the claws ; tail slender, naked, glossy bhick, 

 white at the end. Size of a common rat [Mus decumanus) . 

 Hah. Panama {Boucard). 



Nesokia. 



Skull short, broad, broader than half the length (1| to 1). 

 The nose short, slender, and compressed. Slit before the orbit 

 narrow, expanded and oval above, thickened on the front 

 edge. 



Nesokia koh. N. hydropliorus. 



Heliomys. 



The skull rather broad, flat above, about once and two thirds 

 as long as wide at the back of the orbits Orbits wide. Fore- 

 head between the eyes narrow, with a ridge on each side, and 

 the sides parallel. The cavity before the eyes triangular, deep, 

 not so long as high, above with a straight, scarcely lamellar, 

 hinder edge, and a thickened, shelving, convex front edge. 

 Palatine groove elongate. Nose rather broad. 



I do not know the animal belonging to this skull, which we 

 received from Professor Jeude from the Utrecht Museum ; but 

 it is exceedingly different from the skulls of all the rats which 

 I had previously seen, by its breadth, the spreading of tlie zygo- 

 matic arch, the narrow forehead between the eyes, and the 

 peculiar form of the a])crture in front of the orbit, and also by 

 the thickening of the central })art of the substance of the central 



