1896.] GENERA. OF RODENTS. 1021 



92. Evotomys, Coues. 



P. Ac. Philad. 1874, p. 186. 



93. Microtm, Schrank. 



Piiuna Boica, i. p. 60 (1798). [^Arvicola, 

 Lac. Mem. de I'lust. iii. p. 495 (1801).] 



(6) 94. Synaptomys, Bd. 



Maram. N. A. pp. xliv, 558 (1857). 



95. Lemmus, Link. 



Zool. Beytr. i. pfc. 2, p. 75 (1795). [Myodes, 

 Pall. Zoogr. Eoss.-Asiat. p. 173 (1811).] 



96. Dicrostonyx, Glog. 



Naturgesch. p. 97 (1841). [Cuniculus, 

 Wagl. Isis, 1832, p. 1220.] 



(c) 97. ElloUus, Fisch. 



Zoognosia, iii. p. 72 (1814). 



L. Siphnein^e'. 



98. Siphneus ', Bts. 



I-Iet geslacht d. Miilzen, p. 20 (1827). 



VII. Spalacidae'. 

 A. EhizomtinjE. 



99. Shizomys, Gray. 



P. Z. S. 1831, p. 95. 



• Mr. &errit Miller, to whose paper on Voles and Lemmings I am much 

 indebted, has thrown doubt on the validity of the Siphneincs as a subfamily 

 (N. Am. Fauna, no. 12, p. 8, footnote, 1896), and in so far as regards Ellobius, 

 hitherto always put with Siphneits, he is apparently correct, as its differences 

 from the Voles and Lemmings do not seem to be much greater than those that 

 separate these two groups from each other, and the Voles, Lemmings, and 

 Ellobius may suitably form three groups of the subfamily Microtince. I have 

 had to reverse the order of the genera from that given by Mr. Miller, in 

 order to bring the Murine FJienacomys and Evotomys towards the Muridse, 

 Synaptomys towards the Voles, and tlie Lemmings, as a whole, towards Ellobius. 



With regard to Siphnetis itself, however, I think its peculiarities are amply 

 sufllcient to necessitate its being set over against all the rest of the group in a 

 subfamily by itself. The modification that its anteorbital foramen has under- 

 gone, in comparison with that of the Microtincs, is, however, curiously paralleled 

 by that of the widely different SpalacidcB, and may be simply an adaptive 

 modification due to a strictly talpine life. But in any case its differences, both 

 external, cranial, and dental, are clearly sufficient to demand separate subfamily 

 rank. 



= Dr. J. A. Allen, Bull. Am. Mus. N. H. vii. p. 183 (1895), considers Kerr's 

 Myoialpa should replace Sipkneits ; but as the result is attained by a method 

 about the detailed working of which opinions are still divided, I provisionally 

 use tlie better-known term. 



' Not only do the Baihyerginm of Alston's Spalacidm of course go off to form 

 a separate family, but it is very doubtful whether Spalax and Bhisomys, combined 

 by him in the Spalacina, are rightly put even in one family, their resemblances 

 being perhaps more adaptive than genetic. Winge puts Ehizomys with the 

 Murida3, and Spalax with the Dipodida;, but does not give sufllcient reasons 

 for these allocations. This is one of those cases where a myological investigation 

 is likely to be of much service ; and the group is commended to the attention of 

 Mr. Parsons, whose recent papers on Rodent myology have been of muqh 



