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Show 1890.] ON THE GENERA OF THE FAMILY SORICID.E. 49 2. A Synopsis of the Genera of the Family Soricidce. By G. E. DOBSON, M.A., F.R.S. [Eeceived December 21, 1889.] The following synopsis of the genera of the family Soricidce has been based on a very careful examination of a great number of specimens representing nearly all the known species, and differs from preceding synopses and classifications not only in the number and mode of arrangement of the genera, but also in many of the characters used for their discrimination1. In such a very compact family it is extremely difficult to obtain characters sufficiently salient to distinguish the genera when presented in synoptical form, and I a m well aware that the discovery of new species may render changes inevitable in the definition of some of the genera as given below. While certain species, such as Sorex vulgaris and Blarina brevicauda, are easily relegated to their respective genera, this is not so readily effected with other species in which many of what appear to be the most important generic characters are either feebly developed or are altogether absent. So closely, indeed, are the species allied, all possessing the same number and character of mandibular teeth (Myosorex varius, in which there is a seventh pair of rudimentary lower teeth, can scarcely be considered an exception), that it is probable that the only really natural division of the Shrews is into two sections, one including the white-toothed and the other the red-toothed species. I. Teeth red-tipped Subfamily SOEIClNvE. a. Tail clothed with equal or subequal sized hairs; glans penis cylindroid or tapering. (Terrestrial, rarely aquatic.) a'. Opening of male or female generative organs separated from the anal orifice. a". Ear-conch well developed; tail long. Dent. *' 4~42'pm-|--g; m - 3 ~ 3 = 32 teeth SOREX. mand. b-b 1 Most of the synopses and classifications of the genera were based upon the dental formulas of which a resume is given in Brandt's well-known papers on the dentition of the Shrews (Bullet. Soc. Imp. Nat. Moseou, t. xii. 2e part. pp. 76-95, 1868, t. xliii. 2e part. pp. 1-40, 1871). Since the appearance of Brandt's work A. Milne-Edwards published in 1872 (Eecherches pour servir a l'Hist. Nat. des Mammiferes, p. 259) a synopsis of the genera of this family, by far the most noticeable of the classifications which had yet appeared. This classification was adopted by m e in the article " Mammalia," Encyclop. Britannica, 9th edition, 1882. 2 Brandt (I. c.) has clearly shown that the position of the premaxillary suture in Sorex vulgaris and in S. minutus is between the third and fourth unicuspidate teeth, and that therefore there are 4 upper incisors on each side in these species, one more than in any other species of placental mammal not belonging to this family and to be met with among existing mammals in the Marsupialia only. 3 As the anterior maxillary tooth is neither functionally nor morphologically a canine in any species of this family, I have not designated it as such in the dental formula?, but have included it in the number of the premolars. PROC. ZOOL. SOC-1890, No. IV. 4 |