MAMMALIA — RODENTIA. 
41 
importance on the form of the under jaw, whilst I have assigned to it 
only a very subordinate importance. In particular, I do not classify 
according to one and the same character, which must always lead to a 
more or less artificial distribution ; but in the fixing of a family, I have 
been guided by those marks which are prominent in it above the rest. 
What my method, by this proceeding, obviously loses in logical con- 
sequence, it gains richly on the other hand, for it can be made to com- 
prehend the genera together in gToups according to nature. On the 
individual families I shall, where it is necessary, in proceeding, speak more 
at large ; and I thus hope to come to an understanding with Waterhouse, 
whose distinguished services to Therology I acknowledge with the high- 
est respect. 
Miram explains, in the Bull, de Mosc. 1841, p. 541, that the merit of 
having first drawn attention to the peculiar little bones on the margin 
of the passage of hearing in the Guinea Pig, does not belong to him but 
to Leuckart. 
The reporter has concluded “ Schreber’s Saugth. Suppl. iii.” with the 
family of the Mice. The fourth supplementary volume will give the rest 
of the Rodentia, and the remaining orders of land Mammalia. 
SciURiNA. — Waterhouse (Ann. x. p. 202) has given a 
wider extension to his family Scmridce, according to the 
following scheme : — 
Family SciuniDiE, with the genera Sciurus, Pteromys, Sciuropterus, 
Xerus, Tamias, Spermophilus, and Arctomys. 
Aherrant Forms (without post-orbital process to the frontals). 
1. With large ant-orbital opening; palate contracted between the 
anterior molars... ... ... ... ... Anomalurus. 
2. With small ant-orbital opening. 
a. With rootless molars ... ... ... |— | — Aplodontia. 
h. With rootless molars ... ... ... | — (Sciuridce?) 
a. Folds of enamel simple ... Ascomys. 
b. — ■ — complicated ... ... Castor. 
I cannot agree with the union of these aberrant forms to the Squirrels, 
just because they are aberrant, and could find a legal place elsewhere. 
I consider Anomalurus to belong to the Myoxince, according to the few 
notices which are given of it. Aplodontia and Ascomys rank naturally 
with the Jumping Mice ; and this shows how necessary it is to have 
characterized a peculiar family, Cunicularia, as Pallas had asserted ; 
otherwise the genera of this group must have been scattered among the 
other families, and these would then have been deprived of their natural 
character, as the other classification is a forced one. The addition of the 
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