FAMILY MURID.E. 81 



Length of the head, 1*5. 



Ditto of body, 5 • 5. 



Ditto of tail, 7'9. 



This animal is also supposed to have originally been derived from Europe, and thence trans- 

 mitted to America. It is smaller than the preceding, and is generally thought to have disap- 

 peared before it ; at any rate, it is now exceedingly rare. It is said to breed several times in 

 the year, producing from six to twelve at a litter. Like the preceding, it is omnivorous. 



THE AMERICAN BLACK RAT. 



MUS AMER1CANUS. 

 PLATE XXI. FIG. 1. — (COLLECTION OF J. G. BELL.) 



Characteristics. Black above, leaden beneath. Ears higher than broad. Tail shorter than 

 the body. Length 15 inches. 



Description. Ears large, dilated and rounded, almost entirely naked, sparsely furnished 

 with short hairs. Whiskers black, numerous, extending to the hind head. Fore feet feeble, 

 with five tubercles on the soles. Claws horn-colored, small, acute, incurved ; the toe next 

 to the internal longest. Hind feet with four tubercles arranged quadrilaterally ; toes longer 

 and more robust than on the fore feet ; claws stouter, and not so much incurved. Muzzle 

 bifid. Nostrils lateral. Tail cylindrical, tapering regularly to the tip : the annulations about 

 a hundred and forty, covered sparsely with short hairs, which extend • 2 beyond the tip. 



Teeth. In the lower jaw, the incisors are longer than those above. The molars gradually 

 diminish in size ; the first largest, with two cavities ; the anterior trilobate in front, and sepa- 

 rated by a waved transverse ridge from the adjacent tooth ; the second with two smaller ca- 

 vities, separated in the same manner. The posterior tooth smallest, with two cavities, the 

 ultimate space rounded. 



Color. Above uniformly black, the fur at the base slightly fulvous ; beneath, of a uniformly 

 leaden hue. Incisors yellowish. Fore toes whitish, with a rufous tinge on the inside. 



Length of head, 2*4. Height of ear, - 75. 



Ditto of body, 7"0. Width of ditto, 0'45. 



Ditto of tail, 6*0. Girth of body at shoulders, 7 -00. 



We cite no synonimes, as we believe the species to have been either unobserved, or con- 

 founded with the imported Black Rat of Europe. It is very rare. The only specimen I have 

 ever seen was brought to me in a recent state by Mr. John Bell, when the fur was distinctly 

 black. After having been mounted for several months, the fur assumed a more brownish hue. 

 It appears to differ from the decumanus in its teeth, the number of its annulations, position of 

 the mouth, and proportion of its ears ; from the rattus, in its dentition, relative length of ears, 

 and tail. 



Fauna. 11 



