ANNULATED MARMOT SQUIRREL. 215 
GEOGKAPllIOAL DISTRIBUTION. 
The specimen we have described above, was obtained on the Western 
Prairies, we believe on the east of the Mississippi river ; the locality was 
not particularly stated. It was politely presented to us by Professor 
Spencer F. Baird, of Carlisle, Pennsylvania, a young Naturalist ot emi- 
nent attainments. 
general remarks. 
In every department of Natural History, a species is occasionally found 
which forms the connecting link between two genera, rendering it doubt- 
ful under which genus it should properly be arranged. Under such cir- 
cumstances, the Naturalist is obliged to ascertain, by careful examination, 
the various predominating characteristics, and finally, place it under t o 
genus to which it bears the closest affinity in all its details. The feper- 
mophili are intermediate in character between the Squirrels and Mar- 
mots. They have the lightness of form of the former, and burrow m the 
ground like the latter. By their cheek pouches, of which the true Squir- 
rels and Marmots are destitute, they are distinguished from both. The 
second inner toe on the forefoot of the Spermophili is the longest, whilst 
in the Squirrels the third is longest. But in these closely-alhed 
genera, there are species which approach those of another genus. 
Thus our Maryland Marmot, (ffi Monax,) has a rudimentary cheek-pouch, 
in which a pea might be inserted, yet in every other particular it is u 
true Arctornys. The downy Squirrel, {ScAurus lanugmosas, see Journa 
Acad. Nat. Science, Vol. 8th, part 1st, p. 67,) by its short ears, broad 
head, and not very distichous tail, approaches the Spermophili, yet by Us 
being destitute of cheek-pouches, by its soft, downy fur, and its hooked, 
sharp claws, of which the third, as in the Squirrels, is longest, it is more 
allied to Sciurus. On the other hand, the species now under considera- 
tion has the long legs, slender form, and sharp, hooked claws ot the 
Squirrel The two middle toes of the fore-feet being of equal lengt , 
prove its affinity to both genera i but in the general shape of its body its 
Lek ponches/its short ears, and smooth, rigid hair, it most be regarded 
a.s belonging to the genus Spennophilns. We consider this species and 
the downy Squirrel as connecting links between Sciurus and Spermm 
philus, as we regard Sciuru, U„Uonk^< the connecting link between 
Tamias and Sciurus. 
