462 THE ANOMALURES CHAP. 
as onawing and excavating tools as well as for the purposes of 
alimentation; for it allows of substances being gnawed away - 
without the products of the chisel-lke action being taken into 
the hinder cavity of the mouth. The Rodents have for the most 
part a simple stomach of normal form; but in a few this is 
complicated by a marked constriction, which divides the cardiac 
from the pyloric portions. The Hamster, for example, is thus 
characterised. In all the members of the order, with the excep- 
tion of the Dormice and some allied forms, the caecum is large 
and often sacculated. In some forms (e.g. Arvicola, Myodes, 
Cuniculus) the large intestine is coiled upon itself in a spiral way 
a state of affairs strongly suggestive of Ruminants. 
The Rodents are primarily divisible into two great groups, the 
Simplicidentata and the Duplicidentata, characterised mainly by 
the upper incisor teeth. In the former there is but one pair of 
these teeth; in the latter a second smaller pair he behind the 
former. 
SUB-ORDER 1. SIMPLICIDENTATA. 
SECTION 1. SCIUROMORPHA. 
The Anomaluri are separated by Thomas and others from this 
section as an equal “section, while by Tullberg they are grouped 
with Pedetes. 
Fam. 1. Anomaluridae.—The genus Anomalurus suggests at 
first sight the Flying Squirrels of Asia, Pteromys. It 1s, how- 
ever, an entirely African genus, and is to be distinguished from 
the Asiatic Rodents by a series of scales at the root of the tail, 
imbricated, keeled, and forming possibly a “climbing organ.” 
This character serves also to distinguish the present genus from 
Sciuropterus. The cartilage, moreover, which supports the 
patagium springs from the elbow. There are four molars in each 
half of each jaw. The eyes and ears are large. There are five 
fingers and toes, but the thumb is small, though provided with 
a nail, The sternum has seven joints, and nine ribs reach it. 
The clavicle is strong. Huet, who has recently monographed the 
genus,’ allows six species. The species vary in size. 
1 «Observations sur le genre Anomalurus,” Nouv. Arch. Mus. (2), vi. 1883, 
