158 ZOOLOGY. 



Castor coypiis, Fischer, Synopsis, 1829, 288. 



3fyopotamus honariensis, Kengger, Saiig. von Paraguay, 1830, 237. 



3Iastonotus poijelairi, Wesmael, Bull. Acad. Eoy. de Brux, 1841, 61. 



Gtiillinomys cliilensis, Lesson. Nouv. Tab. du E. A. 1842, 126. 



VuLG. Coypu and Nutria. 

 From the preceding list of synonymes, -wliicli might have been greatly extended, it will he 

 seen that the position among rodents of this large sj^ecies has occupied to a considerable 

 degree the attention of systematic zoologists. Until quite recently it has been placed near the 

 beaver of North America, to which, by the fineness of its fur and some of its features, it bears 

 a considerable resemblance. Its position has, however, been established by Waterhouse among 

 the Hystricidce, sub-family Echimyina, where it seems really to belong ; the affinities of Castor, 

 on the other hand, being essentially with the squirrels. 



This species is the one which furnishes the nutria fur of commerce — an article which, from 

 its abundance and excellence, has greatly depreciated the value of skins of the North American 

 beaver and muskrat. It is found all through temjjerate South America ; but it is in the river 

 district of La Plata and in the Chonos archipelago that the skins are principally collected for 

 purposes of commerce. It is strictly aquatic in its habits, much resembling the muskrat of 

 North America, and, like it, feeds partly on vegetable substances and partly on shell-fish. The 

 flesh is white and well flavored. 



There is a peculiarity in the position of the nipples of the Coypu, found, indeed, in others of 

 the Hystricidce., but here most strikingly manifested, namely : in their situation on the back, 

 or at least above the middle line of the flanks ; the foremost is placed behind the shoulders, 

 and the last one in front of the thigh. The object of this feature is to permit the young to 

 reach the mammaj from the back of the jjarent while she is swimming in the water, in which 

 most of their time is passed. 



According to Waterhouse and Darwin, the precise range of this species, on the east side of 

 the Andes, is from Peru to the Eio Chupat, in 43° 20', although it has not been noticed by 

 naturalists in eastern Brazil. West of the mountains it extends from about latitude 33°, or 

 central Chile, to 48° south, or still further, but not to Tierra del Fuego. 



HESPEEOMYS. 



The collection of Lieutenant G-illiss contains two specimens of Hesperomys, which, however, 

 I have been unable to identify, owing to their imperfect condition. 



CHLAMYPHOEUS TEUNCATUS, Harl. 

 Plate XI. 



Chlamypliorus truncatus, Harl. Ann. N. Y. Lye. I, Jan. 1825, 235. 

 Ib. Med. and Phys. Ees. 1835. 

 Ib. Zool. Journ. II, 1825, 163, PI. vi. 



Yarrell, Zool. Jour. Ill, 1827, 544, PL xvi, xvii, (Osteology.) 

 ChlamydopJiorus truncatus, Wagner, Suppl. Schreber, Mam. IV, 1844, 187. 



Hyrtl, Sitzb. K. Ak. Wien. Math. Nat. XII, March '54, 79. 

 VuLG. PicJiiciego. 

 This species, which has for a long time excited the interest of naturalists since its first 

 description by Harlan, is still very imj^erfectly known, and but few specimens have, even at 

 this late day, been received into collections of natural history. It was first brought to Phila- 

 delphia by Mr. W. Colesberry, who obtained it from Mendoza, and furnished almost the only 

 information we yet have of its habits. This specimen was given to Peale's Museum, where it 



