| 1884. ] Zoblogy. 1275 
From this table it will be seen that the carnivorous Dinosaurs 
= stand in xo direct genetic connection with the birds. There is no 
_ “postbubis” in the carnivorous Dinosaurs; these forms seem to 
_ become extinct in the Cretaceous, leaving no descendants. 
_ _ Inthe herbivorous Dinosaurs and especially in the ornithopod- 
_ like forms we must seek for the ancestry of birds, and evidently 
_ that of the Ratitz, the Carinate being thus considered as de- 
_ Scending from the Ratite. It is not at all evident that Archeop- 
_ teryx belongs in the carinate line as Dames believes.—Dr. J. G. 
4 Baur, Yale College Mus., New Haven, Conn., October, 1884. 
_ THOMASOMYs, A NEW SUBGENERIC TYPE OF HeEspERoMys.—We 
have been greatly interested in the progress of Mr. Oldfield 
_ Thomas's studies of South American Muride—a difficult group 
_ on which we think this author has succeeded in throwing much 
_ Needed light. His latest paper, a valuable one upon Jelski’s Pe- 
_ fuvian collection (P. Z. S. June 17, 1884), divides the unwieldy 
_ genus Hesperomys into the following groups: Rhipidomys, Ory- 
_ tmys, Calomys, Vesperimus, Onychomys, Scapteromys, Phyllo- 
abrothrix and Oxymycterus. Mr. Thomas's arrangement 
shows “ that the name Calomys is restricted to the small group 
to which it was originally applied by Waterhouse; that Oryzo- 
mys, which was hitherto supposed to include only two North 
_ and Central American species, really contains the great mass of 
e South American vesper-mice to which Calomys has been 
monly applied; and that the range of Dr. Coues’s subgenus 
rimus extends down as far south as Peru, since it contains 
he two species X. cinereus and H. taczanowski, formerly placed 
by me with much doubt in Rhipidomys, but which I now think 
Must either be referred to Vesperimus or be made the type of a 
v subgenus ” (I. c., p. 450). : 
aving lately, through Mr. Thomas's courteous attentions, 
able to inspect these two species in the British Museum, we 
its monticoline. Type, Hesperomys cinereus Thos. = 
“tho Oldfield Thomas, Esq., assistant dept. of mammals, Br. 
valuable 
ear was the announcement 
ols t ia, that Mr. W. H. Caldwell, who went there for the purpose 
$ 
