THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



No. 49. OCTOBER 1841. 



IX. — Observations on the Rodentia. By G. R. Waterhouse, 

 Esq., Curator to the Zoological Society of London. 



[With a Plate.] 

 [Continued from p. 600, vol. iii., N. S., of the Mag. Nat. Hist.] 

 Family VI. Bathyergid^e. 

 This family appears to be entirely confined to Southern Africa, 

 and is composed of but few known species, and these consti- 

 tute the two genera Bathyergus of Illiger and Orycterus of F. 

 Cuvier. 



The situation which the Bathyergidm should occupy among 

 the Rodents is difficult to determine. They agree with the 

 Hystrices, Capromys, Echimys, &c. in having the descending 

 ramus of the lower jaw thrown out from the outer side of the 

 alveolar portion ; but in the genera just mentioned the de- 

 scending ramus is of a triangular form, and the posterior 

 angle is produced and pointed. They moreover always have 

 a large ant-orbital opening, the palate is almost always deeply 

 emarginated behind, and the malar bone is deep and com- 

 pressed. These and other characters which I shall have to 

 notice in my next paper, I seek for in vain in the Bathyergidce ; 

 and on the other hand, when I turn to the Murine or Sciurine 

 groups, I do not find a single example in which, combined 

 with other characters peculiar to those groups, the descending 

 ramus of the lower jaw is not thrown out from the under side 

 of the alveolar portion. Of the Bathyergidce I am acquainted 

 with but four species*, and of only two of these have I had 

 an opportunity of examining the skulls, viz. Bathyergus ca- 

 pensis and Orycterus maritimus. 



Their chief characters are as follows : — 



Dentition. — Incisors broad; molars |~ or ~^, subrooted, 

 small, equal, or very nearly equal, in size, and the series on 

 each side of each jaw parallel. 



In Bathyergus the incisors of the upper jaw are less curved 

 than in most Rodents, and remarkable for their great length, 



* Bathyergus capensis, Desm., B. ccecutiens, Licht. (which is the B. 

 Hottentotus of Lesson and Garn., and the B. Ludivigii of Dr. Smith), B. 

 Damarensis, Ogilby, and Orycterus maritimus. 



Ann. §• Mag. N. Hist. Vol. viii. G 



