1906.] NATURAL SCIENCES OF PHILADELPHIA. 293 



FURTHER KNOWLEDGE OF SOME HETEROGNATHOUS FISHES. PART I. 

 BY HENRY W. FOWLER. 



In this paper I have attempted to arrange systematically the Heter- 

 ognathi contained in the collections of the Academy of Natviral Sciences 

 of Philadelphia. This group is largely made up of collections formed 

 by John Hauxwell, James Orton and H. H. Smith. Nearly all of 

 Cope's typical specimens, besides a number of comparatively rare or 

 obscurely defined species, are represented. Owing to the increase in 

 knowledge of the vast fresh-water ichthyic fauna of South America, it 

 is believed that further detailed information concerning rare, nominal 

 or species only known from the original specimens will be welcomed. 



ERYTHRINID^. 

 Hoplias malabaricus (Bloch). 



Macrodon trahira Cope, Proc. Amer. Philos. Soc. Phila., XI 1SG9-70 



(August 19, 1870), p. .5GG. Pebas. John Hauxwell. Cope, Proc. 



Acad. Nat. Sci. Phila., 1871 (January 16, 1872), p. 257. Ambyiacu River. 



John Hauxwell. Cope, Proc. Amer. Philos. 8oc. Phila., XVII, 1877-78 



(May 17, 1878), p. 694. Peruvian Amazon. Prof. J. Orton. 

 Macrodon tareira Cope, I.e., XXXIII, 1894 (Januarj'^ 5), p. 84. Brazilian 

 province of Rio Grande do Sul. H. H. Smitli. 



A series of 28 examples represented by those in the Hauxwell and 

 Orton collections from the Ambyiacu and Peruvian Amazons, and the 

 H. H. Smith collection from Rio Grande do Sul, also others from Bahia, 

 Rio das Vehlas and Surinam. They show: Head 2f to 3^; depth 3f to 

 51; D.ii or iii, 10 1 to 12 1, mostly 111, and only rarely 10 1 or 12 1 ; A. ii or 

 III, 8 I or 9 I, most always 8 i, or only rarely 9 1 ; scales 36 to 42 in lateral 

 line to base of caudal, with 2 to 4 more on latter; 6 scales obliquely back 

 from origin of dorsal to lateral line, only rarely 5 ; between lateral line 

 and base of ventral 5 or 6 scales, usually 5; 15 to 19 scales before 

 dorsal; snout 4 to 4| in head, measured from tip of upper jaw; eye 

 41 to 8; maxillary If to 2^; interorbital 3^ to 4f; total length of 

 body 2{ to 12^ inches. 



OPHIOCEPHALOPS subgen. nov. 

 Type Erythrinus unitoeniatus Agassiz. 



Dorsal fin rounded or posterior rays not elevated. 

 i!'0<pi<s, serpent; ice<paXr^, head; w^'-, appearance.) 

 20 



