438 Bibliographical Notices. 



The second portion of M. De Selys-Longchamps' work treats of 

 the European species of Mus, L., which are all retained under one 

 genus, admitting, however, of two sectional divisions as follows : 



I. Omnivorous; ears ohlong, naked: containing six species, viz. 

 M. decumanus, Pall. ; M. Alexandrinus, Geoff. ; M. Rattus, Lin. ; 

 M. Musculus, Lin. ; M. Islandicus, Thienem. ; M. sylvaticus, Lin. 



IL Granivorous ; ears rounded, hairy : containing two species, 

 viz. M. agrarius, Pall., and M. minutus, Pall. The former of these 

 is stated to be at the limits of the two groups, having the general 

 form of M. sylvaticus, with the ears of the second group. 



To the above, another section is prefixed, containing what he 

 terms Rats echimoides, or those species the fur of which is mixed up 

 with sharp prickly hairs, as in the genus Echimys. This group, how- 

 ever, is entirely exotic, inhabiting the intertropical countries of Asia 

 and Africa. 



It is not pretended that these divisions are capable of such strict 

 definition as to be applied rigorously, but it is thought that they are 

 sufficiently natural, taking them in the whole, without going into 

 details. 



With regard to the species of this genus, the author observes, that 

 they have been much less confused than those of Arvicola and Sorex, 

 if exception be made of the M. minutus (the Harvest Mouse of En- 

 glish authors), the synonymy of which we think he has sufficiently 

 cleared up. As for the others, it is principally in relation to their 

 habitats and their diagnostic characters that he has found any oc- 

 casion for making new remarks. The M. Alexandrinus, first described 

 by GeofFroy St. Hilaire in the great work on Egypt, is here consi- 

 dered to be the same as the M. Tectorum of Savi and the Prince of 

 Musignano, although regarded as distinct by the two authors just 

 mentioned. M. De Selys-Longchamps has pointed out the insuffi- 

 ciency of those characters which have been resorted to as grounds for 

 separating them. The M, Hibernicus of Thompson, he has noticed in 

 an appendix along with two Sicilian species discovered and described 

 by Rafinesque, the M. frugivorus and the M. Dichrurus, concerning 

 none of which he offers any opinion, as they have not fallen under 

 his own observation. At the same time, in reference to the first, he 

 states, that if the colour of the fur is constant, and especially if the 

 difference in the length of the ears between it and the M. Rattus is 

 not caused by the way in which the animal is prepared, he should 

 be tempted to admit it as a species. In another place he suggests, 

 whether it may not be a hybrid between the M. Rattus and the M. 

 decumanus. He adds, however, that this is not likely. 



The genus Arvicola, which forms the subject of the third mono- 



