ADDITIONAL OBSERVATIONS. 
12 * 
40( 2 ). Didelphis californica. Zool. pr. for 1833, page 40. 
This is the name given by Mr. Bennett to an opossum from California, easily distinguishable from 
previously described species. 
40( 3 ). Didelphis breviceps. 
This is another new species from the same locality, also described by Mr. Bennett. As it may have been 
one of these two species which was observed by Mr. Collie at Monterey, the existence of the Virginian 
opossum on the north-west coast remains to be ascertained. 
46. ARCTOMYS CAL1GATUS. 
There is a living animal of this species now in the Zoological gardens. It was brought to England by 
Mr. King, surgeon to Captain Back’s overland expedition, and is figured and described in his recent work 
under the appellation of arctomys ochanaganus derived from the river upon whose banks it was caught. The 
arctomys pruinosus of Pennant is perhaps the same with caligatus, but the brief account of it in Arctic 
Zoology is insufficient for correct determination. 
49( 2 ). Spermophilis spilosoma. Californian souslik. Zool. pr. 1833, p. 40. 
This spermophile very nearly resembles the American guttatus ? which was so named from an unwilling- 
ness to give a new specific appellation to an American animal while unable to point out characters by which it 
may be distinguished from the almost similarly spotted Asiatic souslik. Since the publication of the Fauna 
B or eali- Americana 1 have received a number of sousliks from the Rocky Mountains, differing from each other 
very considerably in size, but agreeing exactly in all other external characters with the description contained 
in that work. From the very greasy condition of all these skins it would appear that this is the fattest of all 
the American spermophiles. 
51. ( 2 ). Spermophilis macrourus. Zool. pr. for 1833, p. 40. 
This Californian marmot, described by Mr. Bennett, is nearly allied to sp. Beecheyi and Douglasii, dif- 
fering from them chiefly in its black head and somewhat longer tail. 
54( 2 ). SciURUS NIGRESCENS. Benn. Zool. pr. 1833, p. 41. 
The Zoological Society obtained a skin of this squirrel from California, at the same time with those of 
several of the preceding animals. In the Proceedings of the Zoological Society, for 1836, page 88, there is a 
notice by J. E. Gray, Esq. of Sciurus Douglasii. collected by the lamented naturalist whose name it bears, 
on the north-west coast. 
55( 2 ). Geomys Townsendii. 
Dr. Bachman kindly submitted to my inspection specimens of two kinds of sand-rat taken by 
Mr. Townsend on the plains of Columbia. One, the G. Douglasii, has a rustv-brown coloured fur above, 
hair-brown on the abdomen, and blackish head. Tail, feet, and pouches, white. Townsendii differs in 
having the wood-brown coloured back of borealis, and is distinguished from the latter by its longer tail. 
Total length of head and body of G. Towsendii, 7f inches, of tail, ‘2| inches. An individual of G. borealis 
of equal size of body, has the tail a very little exceeding an inch in length, and just equal to that of a young 
specimen of Townsendii, whose head and body measures only 5J inches. 
