270 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



Tefragoiioptems scabn'piiinisK.n&r [no\.]tnyns), Characinen, 39, 1859 (Xam- 



apa, Mexico ; Irisanga) ; Giinther, Cat. Fish. Brit. Mus. V, 325, 1864 



(in part). 

 Tetvagonoptevus jnicrostonia Giinther, Cat. Fish. Brit. Mus. V, 323, 1864 ; 



Gunther, Ann. & Mag. Nat. Hist. July, 1880 (Rio Plata). 

 Tetyagonopterus ceneus, Hensel (not Gunther) ; Wiegm. Archiv. 1870, 87 



(Southern Brazil). 

 Tetyagonopterus jeqnitinhoiihce Steind., Siisswf. Siidostl. Bras., Ill, 27, 



pi. ii, fig. 3, 1876 (Jequitinhonha) ; E. & E., Proc. U. S. Nat. Mus., 



XIV, 1891, 52; Ulrey, Ann. N. Y. Acad. Sci. VIII, 280, 1895; 



Eigenmann & Norris, Revista Museo Paulista, 357, 1900 (Piracicaba). 

 Habitat : Rio Negro, Patagonia to Mexico, in all streams of the east- 

 ern slope of South America ; Western Ecuador. 



Of this species Steindachner says: "Almost every river system pos- 

 sesses a peculiar variety of this species ; according to age, sex, season ; 

 according to abundance or scarcity of food ; according to the habitat in 

 cool or clear mountain brooks or deeper stagnant waters, the outlines of 

 the body vary, and in part also, the number of horizontal rows of scales 

 and of the anal rays." 



A single specimen has been recorded from the Rio Negro. It is pre- 

 served in the British Museum and is reproduced in fig. 4, plate XXXIV. 



Order IV. HAPLOMI. 



Cope, Proc. A. A. A. Sci., Indianapolis, 1872, 328 and 333; Gill, East 

 Coast Fishes, 1872, 14. 



"Air-bladder, if present, communicating with the digestive tract by a 

 duct. Opercle well developed. Pectoral arch suspended from the skull ; 

 no mesocoracoid arch. Fins usually without, rarely with a few spines ; 

 ventrals abdominal, if present. Anterior vertebrae distinct, without 

 Weberian ossicles." Boulenger. 



The boundaries of this order are differently conceived by different 

 authors and most of the constituent families are extralimital. It includes 

 three families with representatives in South America. Of these, one, the 

 Poeciliidae, which is dominant in Central America and whose species 

 straggle north through the temperate zone and south to Buenos Aires, is 



