MUSEUM OF COMPARATIVE ZOOLOGY. 217 



scriptions of B. cinerea, B. Berlandieri, and B. exilipes, which constitute 

 section B, it is distinctly stated that the first premolar is smaller than the 

 second. Figures of the skulls of all the species of both sections are given 

 in Pis. XXVIII and XXX, but in no case does the first premolar appear 

 to be quite equal to the second. In regard to section B, there are several 

 circumstances suggestive of its being founded on immature example's of 

 section A, in which the dentition is incomplete.* All the species are di- 

 minutive, and vary but little in size ; the teeth are generally proportion- 

 ally large compared with the size of the skull, as is always the case in 

 young animals, and other characters seem to indicate immaturity. The 

 missin"- premolar is the one we should expect the animal to acquire latest.f 

 All the species of section B come from within the admitted geographical 

 range of the species of section A, one only (B. Berlandieri) possibly ex- 

 cepted. Unfortunately, very young specimens of shrews are extremely 

 rare in collections, and in the large series of Blarinai in the Museum of 

 Comparative Zoology there are none so small as those embraced under 

 Baird's section 15. In several of the smallest of them the fifth premolar 

 is scarcely visible, forming a minute uncolored point on the inside of the 

 jaw. In a single specimen from Middleboro', the smallest of the lot, it is 

 wholly wanting. I regret that I have been unable to examine any of the 

 original types of the species of section B. Between the three supposed 

 species of this section (B. cinerea, B. exilipes, B. Berlandieri) the differ- 

 ences (which seem to consist chiefly in color, especially between the first two) 

 are not greater nor different from those seen in a large series of specimens 

 from Massachusetts or other localities. The differences between the dif- 

 ferent specimens referred to either of the species are also very appreciable, 

 and in some cases (see under cinerea and exilipes in North American Mam- 

 mals) so great that their assignment was very doubtfully made. While 

 the evidence of the existence of so many species of Blarina in the Eastern 

 United States, if really of more than one, is evidently very slight, I do 

 not claim to have fully shown that but the one exists; my design has been 

 mainly to call attention to the great need of a thorough revision of this 



* It is well known that in Scalops aquaiicus the number of teeth in the young is less 

 than in the adult, and this difference has resulted in discrepant statements in respect 

 to its dentition. (See Bachman on the Mole Shrews of North America, in Proc. Bost. 

 Soc. Nat. Hist. I, 40. Aim,, Quad. X. Amer., Vol. I, p. 92.) 



t The species of Sorex are divided into two sections on similar characters, where 

 small size again accompanies the lesser number of teeth. There are o'her circum- 

 stances that render it not improbable that we have here again a section " B," based on 

 immature representatives of a section " A." The number of species of Sorex admitted 

 for the United States, twelve or more, is probably quite too large, though undoubtedly 

 there may be half that number. 



