50 QUADRUPEDS OF MASSACHUSETTS. 



path before you, as if perfectly conscious of his means of de- 

 fence. His head is small, and carried low, which, in connexion 

 with his thick, arched body, imparts to him the appearance of 

 clumsiness, foreign to the Weasels. The female breeds once a 

 year, and produces four or five at a time. It extends to the north 

 of the great Lakes, but is apparently most abundant in an old settled 

 country.* 



ORDER RODENTIA. 



Characters of the order. The order is characterized by the 

 presence of two cutting teeth in the form of chisels in each jaw, 

 and which are separated from the molars by a vacant space ; ca- 

 nines none ; molars have flat crowns, or blunt tubercles ; jaws 

 admit of motion backward and forward, rather than laterally ; 

 the posterior extremities longest ; the number of toes varies ac- 

 cording to the species ; mammas variable also in number ; stomach 

 simple ; intestines long. 



FAMILY VIII. CASTORIDiE. The Beaver Family. 



Genus Castor. Lin. Cuv. Geoff. 



Generic characters. Dental system ; incisors § ; molars £=| ; 

 = 20. Crowns of the molars flat ; toes five, anterior short, the 

 posterior long and palmated ; tail broad, thick, depressed, or 

 flatted horizontally, of an oval form, naked, and covered with 

 scales. 



* In the methodical arrangement of the species comprising the animal kingdom, 

 there are two families which should be placed there, the PhocidjE and the 

 Trichechid.5:, commonly known as Seals. Of the first, there are probably two 

 genera, as at present constituted, the Calocephalus, and the Stemmatojtns ; of the 

 last family, only one genus, viz. Trichechus, which may be an occasional visitant to 

 the coast. 



In relation to the seals, it is proper to remark, that I have but little personal 

 knowledge, my information being derived from books. I deemed it inexpedient, 

 therefore, to furnish any matter for this Report, to which I was unable to add 

 something from my own observation. I have, therefore, omitted the usual descrip- 

 tions, and shall pass at once to the next order. 



