eigenmann: the cheirodontin^. 23 



Head pointed, skull convex above, with parietal and frontal fontanel, the 

 latter very short, not extending beyond middle of eye in adult; mouth terminal, 

 greatly variable in size in different species and with age in the same species (c/. A. 

 dentatus); teeth all in a single series, conical, and usually with a cusp on each 

 margin; those of upper and lower jaw alternating and interlocking when the mouth 

 is closed; those of the side of the lower jaw notably smaller than the anterior 

 teeth; cheeks entirely covered by the suborbital; nares close together; gill-mem- 

 branes free from each other; gill-rakers setiform; tongue slender, free; scales 

 regular, of about the same size, well imbricated, cycloid, firm; caudal naked; lateral 

 line incomplete; adipose well-developed; origin of dorsal near middle of body; no 

 pseudotympanum ; a long pore on the base of the middle caudal ray. 



The genus Aphyocharax is well marked by the very strong armature of the 

 cheeks, the third suborbital and the single postorbital being of the same strength 

 and texture, and leaving but little or any of the cheek naked; the scales are firmer 

 than in any other genus of the subfamily and they have peculiar sculpturing. 

 There are two sub-parallel radial striae on the exposed part of the scales; the 

 circuli are well-marked near the base of the exposed portion of the scale and parallel 

 with the radial striae at this point, or converge toward a median line. 



A. dentatus, alburnus, erythrurus, pusillus, and anisitsi form a series from the 

 large-mouthed dentatus with many maxillary teeth to the small-mouthed anisitsi 

 with few maxillary teeth. Of these A. alburnus and A. erythrurus are scarcely 

 distinct. A. dentatus is the Paraguayan representative, alburnus the Amazonian, 

 and A. erythrurus the Guianian. A. anisitsi similarly is the Paraguayan repre- 

 sentative, A. pusillus the Amazonian. A. melanotus probably belongs to another 

 genus. A. avary is probably a synonym of pusillus. 



At the time A. agassizi was selected as the type of the new genus, Holoprion, 

 I had not seen that species. The genus was erected in view of Steindachner's 

 statement, "oberer Theil des Oberkiefers am ganzen vorderen Rande deutlich 

 gezahnt." While in Vienna, I was able to examine the types. It is certain that 

 they have several teeth along the upper anterior margin, but I was unable with 

 a hand-lens to detect any teeth along the distal portion of the maxillary. It 

 seems possible that the type species of the genus Holoprion lacks the character 

 assigned to the genus. However, there certainly are species with this character, 

 viz. : Paraguay ensis, maxillaris, and possibly nattereri, which may be referred to 

 Holoprion, provisionally retained as a subgenus. If a final microscopic examina- 

 tion of agassizi shows that it actually lacks teeth on the distal portion of the 

 maxillary the name Holoprion becomes an exact synonym of Aphyocharax, and a 



