54 
REPORT ON ZOOLOGY, MDGCOXLIt : 
grey ; legs and tail light brown ; body 5" 9'" ; tail 1" 2'^' ; abundant in 
the northern parts of New York. 4. A. scalopsoides ; head thick ; nose 
blunt ; ears concealed ; fur short, very soft, above light brown, beneath 
bright grey ; body 4" ; tail 10'" : Long Island, — not rare in the neigh- 
bourhood of New York. Differs from A. pensylvanica by its thicker 
head ; by the fur being only half as long and without the longer bristles : 
from A.pinetorum, by its size, and the want of a chestnut-brown hue on 
the cheeks. 
Blasius has given some remarks on the Lemmings, in the Verh. der 
Naturf. zu Braunschw. p. 88. The last under molar has in them four or 
five alternating prisms ; in the Arvicola only three, standing obliquely 
behind each other (not alternating). All the Northern species, as 
Myodus hudsonicus, have convex rounded fore-teeth, which form a bow 
on the edge. The species found farther south, to 64° latitude {M. nor- 
wegicus or lemmus, M. torquatus and lagurus), have fore-teeth with 
single bows running into each other on the anterior surface. The most 
southern form, M. migratorius {Lemmus ohensis, Brandts ; Georhychus 
luteus, Eversm.), which belong to the Kirguisian Steppes, has flat, not 
curved, upper fore-teeth. 
Rathke has furnished a copious account of the Norwegian Lemming, 
with regard to its anatomical relations, in the last publications of the 
Naturf. Gesellsch. in Danzig, 1842, p. 1. 
Mus hetulinus has been found in Sweden by W. Von Diiben. He 
discovered this species at Ronneberga, in the neighbourhood of Land- 
skrona, and described it in the K. Vetensk. Acad. Handl. Stock. 1842, 
p. 175. This discovery points out a wide distribution of the known 
species ; and it is also of importance, as the Prince of Musignano 
observes, since it afforded Nilsson an opportunity of determining that it 
cannot be arranged under Mus, but must be placed under Sminthus. 
Blasius has, in like manner, convinced himself, that the allied species, 
Mus vagus, belongs to the genus Sminthus (Verh. p. 87). 
Castorina. — T he position of the nipples of the Myopo- 
tamus has, since my last year’s report, called forth much 
observation, the most of which is yet deposited with me in 
manuscript. 
It was announced in last year’s report, that a Mr. Popelaire had made 
known a strange animal from Chili, which, among other anomalies, had 
nipples on its back. Wesmael named this wonderful animal Mastonotus 
Popelarii ; and Lesson has since given it a second name, Guillinomys 
chilensis. I esteemed the whole account as fabulous. The assertion 
was, however, not long printed, until the Academy received the K. 
Vetensk. Acad. Handl. for Ar, 1839, Stockh. 1841, in which Fahraeus 
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