General Notes. 207 



lodytes.* It is plain that he intended to include within it the old world 

 Motacilla troglodytes, but as he did not actually mention the technical 

 specific name of that species anywhere in his text, the committees of both 

 the American and the British Ornithologists' Unions agree that T. aedon, 

 later selected from the mentioned American species, and not Motacilla 

 troglodytes, stands as the type. 



Fischer's chapter on the mammal collection in Paris is largely a trans- 

 lation of Lacepfede's "Tableau," with the addition under each genus of 

 the German name of the animals, and frequently with a complete sentence 

 to introduce the name of the most remarkable, characteristic, or typical 

 species on exhibition; rather than to list one such species in Lacepfede's 

 systematic, tabular manner. In case we can not accept decumanus as 

 the type of Fischer's Rattus solely on the ground that it is the only 

 species mentioned, we may consider the Rattus of Fischer simply a new 

 name for the Mus of LacepMe. This is the sole instance where Fischer 

 changed a generic name in his translation of Lacep^de. He probably did 

 it because he considered the Medieval Latin noun Rattus a much more 

 appropriate generic name for the rats than the classical Mus, which was 

 used by the ancients for almost any small mammal, including even the 

 ermine and other carnivores. There is no reason to suppose that he was 

 specially thinking of the German "Ratte" or French "rat" in this 

 connection, as suggested by Thomas; if so there was abundant oppor- 

 tunity to change other generic names in the same manner, and he would 

 have been much more likely to mention the " rat noir" as his example 

 than the "rat surmulot." 



Now in settling a technical case of this kind by rule, it seems to me 

 that we must not arbitrarily assume that LacepMe's Mus is the Mus of 

 Linnaeus (type M. musculus) whatever we may honestly believe to be the 

 actual truth. Lacep^de listed only one species, and that in almost as 

 formal a manner as did later authors like Gray and Fleming who actually 

 ' ' fixed " the types of so many genera. The species listed, Mus decumanus, 

 was unknown to Linnaeus ; Lacepfede does not cite Linnseus in any place ; 

 and his "system" is wholly diflferent from the "Systema Naturae." 

 There is no actual evidence to prove that had he listed Mus musculus at 

 all, it would not have been in some other of his genera which are divis- 

 ions of the original Mus of Linnaeus. The type species of the Mus of 

 LacepMe, then, for this purpose, must be Mus decumanus, and this 

 species must automatically become the type of Fischer's substitute gen- 

 eric name Rattus. 



Had Fischer definitely indicated that his Rattus was a substitute name 

 for the Mus of Lacepfede, and if Lacepfede had cited Linnaeus or even 

 Erxleben as the authority for his Mus, we would instantly dispose of Rattus 

 as a synonym of the Mus of Linnaeus. In the absence of the necessary 

 references to treat the case in this manner, it seems to me that we must 

 accept Rattus as the generic name of the rats, with decumanus {norvegi- 

 cus) as the type species. The name Epimys (type Mus rattus)'^ is then 

 available for those who care to separate the alexandrinus -rattus group 

 from true Rattus. —N. Hollister. 



• Ois. Amer. Sept., Vol. 2, p. 52. 1807. 



t See Miller. Proc. Biol. Soc. Washington. Vol. 23, p. 58. April 19, 1910. 



