8 U. Ss. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
of the upper jaw there are four large teeth, the posterior much the smallest, each with numerous 
points. Between these and the large incisors are three, four, or five simple and much smaller 
teeth ; the last or posterior of these are usually very small. These teeth are conical, and have 
sometimes a small pointed tubercle on the inner side at the base. There are three multicuspid 
molars in the lower jaw, and between these and the incisors are two simple teeth. 
The precise homologies of the teeth of the shrews have been a matter of much controversy, 
especially in regard to the number of true molars, and the nature of the teeth just back of the 
anterior incisors. The most reliable authorities concur in considering the formula to be: incisors 
s=1; premolars 5-5 to $2; molars 5-5; less than the usual number of incisors in mammals, and 
the canines wanting entirely. The teeth between the multicuspid molars and the large anterior 
incisors are sometimes simply called anterior lateral teeth, by way of non-committal. 
The concha is usually provided with two valves or flaps, the more effectually to close the 
meatus ; one formed by the antitragus, the other by the helix. 
The snout is extended some distance beyond the incisor teeth, and ends in a naked mufile 
with the nostrils pierced in the sides. The eyes are very minute, though usually discoverable 
on close examination. The ears are more or less distinct, except in the genus Blarina of J. E. 
Gray, where they are entirely concealed in the dried skin. The feet are nearly plantigrade, and 
usually naked beneath. 
‘¢ The stomach of the shrews has the pyloric portion sometimes very short—sometimes much 
elongated; the coecum is wanting; the liver is five lobed, with a gall bladder; the right lung 
four, the left, one lobed. The testicles and seminal vesicles are much swollen in the rutting 
season and lie in the abdominal cavity ; the external genital apparatus in the male differing from 
that of the female only in the presence of the penis. The uterus is two horned ; the female with 
6-10 teats on the belly. There isa peculiar glandular apparatus on the side of the body, near the 
fore-legs, much developed in the male during the breeding season, but very slight, or wanting 
altogether, in the female or young. 
“¢The Soricine first make their appearance in small number of species during the meiocene 
period, and continue through the diluvial epoch to the present time, without material change of 
form.’”! 1 
The food of the shrews consists chiefly of insects, worms, and mollusks, but they are capable 
of attacking or destroying small vertebrates, and readily devour each other. They are very 
voracious, and require a large amount of animal food. They are nocturnal, and more or less 
aquatic. They do not hybernate, but go about in the coldest weather. The young are born 
blind and naked. ; 
The shrews constitute a very natural group, embracing many species, and have been the sub- 
ject of much critical examination on the part of authors, especially of Wagler, Nathusius, 
Duvernoy, J. E. Gray, Bachman, and others. The Old World species are referable to three 
principal genera, the names of which I shall take from Wagler, as established by Nathusius 
and Wagler : 
1. Crossopus, Wagler. Teeth, 30; four premolars in the upper jaw ; lower incisor with one 
tooth on the cutting edge; points of the teeth colored; feet large, ciliated, with bristly hairs 
on the margins; tail long, with a crest of long hairs on its lower side. 
2. Sorex, Wagler. Ears distinct; teeth, 32; premolars, five; hinder hook of the upper 
} Giebel, Allgemeine Zoologie, Saiigthiere, 1855, 898. 
