60 MR. 0. THOMAS ON THE MAMMALS OF [Jan. 19, 
I cannot agree with Dr. Anderson as to the identity of the 
genera Pteromys and Sciuropterus, which he has united on the plea 
that the dentition is much the same in both, and that the distichous 
arrangementis not purely distinctive of the smaller species, but is found 
partially in some of the larger, while, on the other hand, some of the 
so-called Sciuropteri really have bushy tails. He goes on to say, 
“The wing-parachute in all the members of the group is the same, 
although some naturalists have described it in sagitta as having an 
expansion in front of the fore limb which does not exist in the other 
species ; but this is unquestionably an error.” 
In order to settle the question, I have examined specimens in spirit 
both of Pteromys and Sciuropterus, and I find that not only do both 
have an antebrachial membrane, arising from the back of the cheek 
and inserted in the front of the carpus, but that there really are im- 
portant differences in the development and insertion of the parachutes, 
comparable in some respects to those observable in the wing- 
membranes of the Chiroptera, differences which, as in the case of the 
antebrachial membrane, Dr. Anderson must have overlooked through 
examining dried skins only. 
In Pteromys there is a broad well-defined interfemoral membrane, 
inserted externally at the point where the tendo achillis is attached 
to the caleaneum, and internally to the tail from two to three inches 
from its base, and there is in some of the larger species nearly three 
inches depth of membrane clear of the hind limb. 
On the other hand, in Sciuropterus there is either no interfemoral 
membrane at all, or what there is merely consists of a slight expan- 
sion of skin behind the knee, attached externally to the tendo achillis, 
about halfway down, and internally to the hinder side of the hips 
and never involving any part of the tail. 
The lateral membrane also is distinctly narrower, especially below 
the knee, in Sciuropterus than in Pteromys, although the longer 
fringes of hair in the former hide this fact in dried specimens. 
Adding to these differences the well-known one in the arrange- 
ment of the hairs of the tail, to which I am unable to see the 
exceptions mentioned by Dr. Andersen, and also those in the den- 
tition described by various authors, I think that it will be admitted 
that two such natural groups as Pteromys and Sciuropterus should 
be allowed to stand as distinct genera. 
8. ScrUROPTERUS PEARSONI. Gray. 
a. Machi, 7/5/81. 
This rare species would be naturally expected to occur in Mani- 
pur. It has previously been recorded from Sikkim, Assam, and 
Yunnan. 
9. Scrurus rnpicus, Erxl. 
a. ¢. Gurung R. 8/2/81. 
The present is by far the most easterly locality as yet recorded 
for this species, and extends its known range very considerably, the 
Terai region of Nepal (Hodgson) and Cuttack (Anderson) having 
