98 MAMMALIA. 



any other part. It is rather larger than our Rat; its fur is smooth, and of an 

 ash-colour, bordering on a red. This is the animal, in the opinion of Oli- 

 vier, to which the ancients alluded when they spoke of the Mole as being 

 perfectly blind. 

 From the Rat-Moles themselves should have been separated the 



Bathyergus, Illig. — Okycteres, Fr. Cuv. 

 Which, with the general form, feet, and truncated incisors of that genus, 

 have four grinders throughout. Their eye, though small, is visible, and 

 they have a short tail. 



B. maritimus. (The Maritime Rat-Mole.) Nearly the size of a Rabbit; 

 the superior incisors furrowed with a groove, and the hair of a whitish grey. 



Geomys, Rafin. — Pseudostoma, Say. 

 Which have four compressed prismatic molars throughout, the first double, 

 the remaining three simple; the upper incisors furrowed with a double 

 groove in front; five toes to each foot; the three middle anterior nails, that 

 of the medius particularly, veiy long, crooked, and trenchant. Tliey are 

 low animals, and have very deep cheek-pouches, which open externally, 

 enlarging the sides of the head and neck in a singular manner. One spe- 

 cies only is known, 



G. hursarius. (The Canada Hamster.) Size of a Rat; fur of a reddish- 

 grey; tail naked, and but half the length of the body. Inhabits deep bur- 

 rows in the interior of North America. 



DiPLosTOMA, Rafin. 



The Diplostomse are almost precisely similar to the Geomys, but they have 

 no tail. 



These animals are also from North America. The species before us is 

 reddish, and ten inches in length. 



We now pass to larger Rodentia than these of which we have 

 hitherto spoken, but of which several still have well defined clavicles. 

 Of this number is the 



Castor, Lin. 



The Beavers are distinguished from all other Rodentia by their horizon- 

 tally flattened tail, which is nearly of an oval form, and covered with scales. 

 They have five toes to each foot: those of the hinder ones are connected by 

 membranes, and that next to the thumb has a double and oblique nail. 

 Their grinders, to the number of four throughout, and with flat crowns, 

 appear as if formed of a doubled bony fillet, or so as to show one sloping 

 edge at the internal extremities of the upper row, and three at the exter- 

 nal; in the lower ones it is exactly the reverse. 



Beavers are large animals, whose hfe is completely aquatic; their feet and 

 tail aid them equally in swimming. As their chief food is bark, and other 



