8 U. S. P. B. R. XP. 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 

 zlj premolars ^ to ^; molars ^; 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 muffle 

 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 is a 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 Soricince 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 : 



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. SOBBX, Wagler. Ears distinct; teeth, 32; premolars, five; hinder hook of the upper 



1 Giebtl, Allgemeine Zoologie. Saiigthiere, 1855. 898. 



