MAMMALIA — RODENTIA. 
47 
form of the pads to the hind toes, so strongly developed in the A. indica. 
In it they are compressed, with three to five grooves on each side, and 
crenated on the front edge; hodyS|^"; tail 6"; earl'' 4^'": Candahar, 
at Quettah, 
With regard to the Dipus vexillarius, Blasius thinks that it is not 
essentially ditferent from D. jaculus. 
Duvernoy and Lerehoullet have given a masterly description of the 
Dipiis mauritanicus, Duv., in the Mem. de Strasb. iii. The authors 
have principally compared the anatomical relations most completely, 
with an exactness which brings to mind the beautiful works of Pallas 
and Daubenton. The delineation of the muscles of the hind limbs is 
particularly interesting, as it shows how the latter are fully adapted for 
powerful springing. The chief anatomical peculiarities are rendered 
clear by two beautiful plates. In reference to the geographical distri- 
bution, the authors remind us, that Dipus inauritanicus from the 
western provinces of Algiers, and also the specimens from Constantine, 
are not distinguished from those of Tunis and Tripoli. The Dipus 
inauritanicus, however, is larger, stronger, of a darker hue, and the red 
is more mixed with black, than in the Springing-mouse of Tripoli, which 
is smaller, and lighter red. The latter has likewise a somewhat longer 
and narrower head, and comparatively larger ears. The hairs are, be- 
sides, in the Algerine Spring-mouse, stitf and pretty rough ; in that of 
Tripoli remarkably fine, and as it were, woolly ; and this is also the case 
in the specimens from Constantine, which approach nearer the Tripoli 
than the Algiers Spring-mouse. 
PsAMMORYCTiNA. — The new genus Schizodon from Chili, 
described by Waterhouse, in the Ann. of Nat. Hist. ix. p. 507, 
is allied to the Psammoryctes and Octodon, as well as to 
Ctenomys. 
Fore-feet strong, with large claws for burrowing ; ears of moderate 
size ; molars |, rootless, the crown of each divided into two parts by the 
meeting of the folds of enamel of the outer and inner side, and the sur- 
face of these teeth may be compared to a series of cylinders (two to 
each tooth), which are much compressed in the antero-posterior direction. 
The three foremost molars are of equal size, the posterior one smaller. 
Ant-orbital opening very large, besides a peculiar but very small infra- 
orbital opening. The only species is Sch. fuscus, of the size and colour 
of the common Rat, but with softer fur ; body 9" ; tail 1" 8'" ; ear 5^'" : 
Very common on the eastern side of the Andes, undermining the whole 
country, so that horses are continually plunging into the burrows. 
Figures and further anatomical details are much to be desired. 
Lund has divided the South American Bristle Rats into four genera. 
91 
