The MmTcrat. 107 



with five toes, the edges furnished with stiff hairs, which assist 

 the animal in swimming, instead of the feet being palmated or 

 webbed, hind-toes, slightly palmated. Tail, long, compressed, 

 granular, nearly naked, having but a few scattered hairs. Glands^ 

 near the origin of the tail, wisich secrete a white, musky, and 

 somewhat offensive fluid. Maramse six, abdominaL 



" This genus differs from the Arvicolje in its dentition ; the first 

 inferior molar, has one point more than the corresponding tooth 

 in the latter, and all the molars acquire roots immediately after 

 the animal becomes an adult. We have frequently heard com- 

 plaints made by students of natural history, of the difiiculties they 

 had to encounter at the very outset, from the want of accuracy 

 and uniformity in the works of authors, when stating the charac- 

 ters by which they defined the genera they established. The 

 justness of these complaints may be well illustrated by examining 

 the accounts of the present genus as given by several well-knowa 

 writers. 



" Illiger says it has four molars on each side, ( Utrinqui qua- 

 terni,) see Prodomus systematis mammaliarum et avum, making 

 in all twenty teeth. \Yiegman and Euthe, have g^iven the same 

 dental arrangement, see Handbuch der Zoologie, Berlin, 1832. 

 F. CuviER, who has been followed by most authors, has given it — 

 Incisive f ; Canine f — :f , = sixteen teeth. Griffith, Animal 

 Kingdom, vol. iii,, p. 106, describes it as having — Incisive f • 

 Canine ^=:^ = twenty teeth ; and in his synopsis of the species o-f 

 mammalia, (sp. 532,) its dental arrangement is thus characterized 

 — Incisive |, Canine f=f, Cheek-teeth, f=f, giving to it the ex- 

 travagant number of twenty-eight teeth. This last statement is- 

 most probably only a typographical error. A correct examina- 

 tion and description of the teeth of this genus requires a con- 

 siderable degree of labour, besides great attention and care, as 

 they are placed so close to each other that without a good mag- 

 nifying glass it is difficult to find the lines of separation, and al- 

 most impossible to ascertain their number, without extracting 

 them one by one. 



" The descriptions and figures of their dental arrangement, by 

 Baron Cuvier, and F. Cuvier are correct : see Ondatras, dents 

 des mammiferes, pi. 63, p. 157, and Recherches sur les ossemens 

 fossiles, t. 5, p. 1. 



" Illiger's generic name. Fiber, is derived from the latin word? 

 Fiber, a beaver. There is only one species described as belong- 

 ing to this genus." 



