CLASS I. MAMMALIA: ORDER 7. RODENTIA 



459 



Drummond's Neotome, JV. Drummondii, is nine inches long, yellowish-brown in winter and 

 ash-color in summer, and is found iu the Rock)' Mountains from 30° to 70° north latitude. Gray 

 makes of this a genus which he calls TEONOMA, which is only an anagram of JYeototna. 



The Genus OXYMYCTEELS : Oxymycterus, contains several South American species, 

 among which are the 0. nasutus, of the La Plata country, and 0. scalojjs, of Chili. 



The Genus AKODOX comprises the A. Boliviense, of Bolivia and Peru. 



The Genera REITHRODON, PHYLLOTIS, and ELIGMODONTIA embrace various South 

 American species, but of no interest or importance. The Genus HOLOCHILLS includes the 

 Brazilian Rat, the Mus Brasiliensis of Geoffroy, which is of the size of the Brown Rat. The 

 Yellow Rat, Mus lutescens, resembles the preceding. The Pilori Rat, Mus pilorides, is still 

 larger, and is in many respects peculiar. It is black above and white below, and is found not 

 only in Brazil but in the "West Indies. 



"We now come to the New Holland Muriens. The Genus HAPALOTIS presents several spe- 

 cies. The H. albipes is nearly of the size of a rabbit, but of a mouse-like form, and is chiefly 

 found in New South Wales. The H. Gouldii and H. melanura are of New Holland. 



Genus HYDROMYS : Hydromys. — Of this there are two species, the Yellow-bellied Hy- 

 dromys, H. chrysor/astei; and the W t hite-bellied Hydromys, H. leucogaster. Both are of a 

 chestnut color above, but one is yellow and the other white, beneath. They are found along the 

 Swan River. 



MCS ALBOCINEREUS. 



Beside the animals forming the two preceding genera, Australia has been found to possess a 

 number of veritable species of the Mus genus. The distinguished naturalists Gray and Gould 

 have given us descriptions of several, among which we may mention the Mus albocinereus, Mus 

 Australis, and Mus Grayii. These are all of small size. 



Genus PITHECHEIRUS : Pithecheirus. — This includes one animal, the P. melanurus, which 

 has puzzled the naturalists, inasmuch as it resembles alike the rats and the opossums, yet cannot be 

 admitted into the department of either, as it has not the feet of the former nor the tail of the lat- 

 ter. Its body is a uniform brown color, the tail being black. It is the size of a large rat, and is 

 found in India and some of the Asiatic islands. 



Fossil Rodentia. — The number of known species of Rodentia now existing is at least six hun- 

 dred ; from the fossil remains which have been discovered of Hares, Porcupines, Agoutis, Cavies, 

 Dormice, Spermophiles, Jerboas, Gerbils, Field-Mice, Lemmings, Water-Rats, &c, Ave have rea- 



