240 = On the Generic Names Rattus and Phyllomys. 
XXV.—On the Generic Names Rattus and Phyllomys. 
By OLprieLp THOMAS. 
(Published by permission of the Trustees of the British Museum.) 
SINCE my paper on Lattus as a generic name appeared in 
the last number of the ‘ Annals,’ two papers, by Messrs. Hol- 
lister and Goldman, affecting the questions there dealt with 
have arrived from America. 
I ventured to hope that no earlier use of Rattus than 
Fischer’s in 1814 would be found, as that would probably 
upset Hpimys for the genus containing the common rats. 
This hope has been disappointed, for Mr. Hollister * has 
found a use by the same author in 1803 T of Rattus for the 
ordinary rats, with type Jus rattus t; and there being no 
way in which we can escape admitting its validity, we must 
discard Hpimys and accept fattus as the generic name for 
the large genus of true rats. 
As a consequence, my attempted use of Rattus for Azara’s 
Spiny-rat fails, and this animal will have to bear the burden 
of Huryzygomatomys as its generic name. 
From the species which have commonly been placed in 
“ Loncheres,” but which, as already shown, must bear the 
name Lchimys, Mr. Goldman § has taken out a certain 
number with simple laminated molars, and for these he 
proposes to use the name Phyllomys, Lund. 
But, in the first place, Phyllomys is antedated by Nelomys, 
Jourdan, whose type is NV. blainville’, which has obviously the 
same laminated upper molars, and, in the second, the north- 
western species caniceps, with, presumably, dabilis and dar- 
ling?, differs from it by having the lower molars also simply 
laminated, which is not the casein Nelomys. I would, therc- 
fore, propose to make a new genus, Diplomys, for these 
species, with Loncheres caniceps, Giinth., as genotype. Other 
species of true Velomys are brasiliensis ||, thomasi, medius, and 
dasythriv. 
* P. Biol. Soc. Wash. xxix. p. 126 (1916). 
+ National Mus. Naturg. Paris, ii. p. 128 (1803). 
{ Mr. Hollister mentions “ M. decumanus” as the type; but the genus 
is distinctly made for the “ Ratte,” French “ Rat,”= Mus rattus, the 
mention of M. decumanus being merely as “ the most remarkable of the 
other species.” 
§ P. Biol. Soc. Wash. xxix. p. 125 (1916). 
| Mr. Goldman unites brasiliensis with armatus, Geoff. ; but the latter 
is the Guiana red-cheeked species, a true Eehimys, and my Loncheres 
guiane is no doubt synonymous with it. 
