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Show 1890.] GENERA OF THE FAMILY SORICID.E. 51 genera of the two subfamilies. Thus Sorex is represented among the white-toothed Shrews by Myosorex, Blarina by Anurosorex, and Crossopus by Chimarrogale and Nectogale. It would seem as if, after the red-toothed Shrews diverged from the white-toothed, development had proceeded on somewhat similar lines in the descendants of both according to similarity of environment and modes of life. To M . Milne-Edwards's list I have added four genera, Soriculus \ Notiosorex, Myosorex", and Chimarrogale3, and omitted one, Neosorex \ from it. I had long suspected the validity of the last-named genus, founded for the reception of Sorex navigator, Baird, and examination of a well-preserved specimen of a Water-Shrew lately described' by me under the name of Sorex hydrodromus, convinced me that these species8 must be merged in Sorex, of which they cannot even be considered as representing a subgenus. S. hydrodromus, although evidently aquatic like Crossopus fodiens, the fringes of the manus and pes being even better developed than in that species, agrees in all other generic characters with those of the genus Sorex as defined in the synopsis above ; but while agreeing with Sorex palustris from the adjoining continent of America in external characters, it differs from it in the proportions of its teeth, resembling in this respect the section of which S. vulgaris is typical, while S. palustris agrees with those represented by S. vagans. No better proof could be afforded of the uselessness of retaining Neosorex as a distinct genus for the American species characterized by the possession of swimming-fringes in the digits, while the tail is simple as in Sorex. These species are in fact aquatic forms of the genus Sorex. As I have omitted Neosorex so I am compelled to omit Atophyrax, although the distinguishing marks of that genus have been so well and clearly described by its founder, Dr. Merriam, through whose kindness I have been enabled to examine the type, A. bendirii7. This species is, as noted by its discoverer, an inhabitant of marshy land, and appears to me to present many characters intermediate between Sorex palustris and the terrestrial species of the genus, differing from the former in the absence of well-defined fringes to the digits, but agreeing with it closely in dentition, in the large size of the infraorbital foramen, and in the remarkable shortness of the angular process of the mandible. In fact there are no leading characters •which would enable me to define the genus, were I inclined to admit it in m y synopsis. 1 See the writer's paper " On the Genus Myosorex," in P. Z. S. 1887, p. 575. 2 Blyth, Journ. Asiat. Soc. Beng. 1855, xxiv. p. 36. 3 This genus was defined by Anderson (Ann. & Mag. Nat. Hist. vol. xvi. 1875, p. 252), subsequently to the appearance of A. Milne-Edwards's synopsis. 4 Neosorex, Baird, Mammals of North America (Eeports of Explorations and Surveys for a Eoute from the Mississippi to the Pacific Ocean, voi. vii. 1857). 5 Annals & Mag. Nat. Hist., Nov. 1889, r>. 374. 6 From comparison of the types of Sorex palustris and S. navigator I am much inclined to doubt the distinctness of the latter species. 7 Trans. Linnean Society of New York, vol, ii. 1884, pp. 217-225. 4* |
