146 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iie 



and Hoplerythrinus. In these two genera the tooth-bearing ecoptery- 

 goid (= the pterygoid of Hoedeman) is firmly attached to, but not 

 fused with, the palatine. The anterior part of the ectopterygoid lies 

 ventral to the palatine in these two genera and can be mistaken 

 easily for palatine dental plates or dermopalatines. The autogenous 

 tooth-bearing bone below the palatine in Hoplias has been described 

 above. 



Determination of the homologies of the tooth-bearing elements 

 associated with the autopalatine of the Erythrininae cannot be stated 

 precisely from the examination of adult stages only. The interpre- 

 tation tentatively adopted here for the morphological situation in 

 Hoplerythrinus is based on the following: The ectopterygoid is pres- 

 ent and often tooth-bearing in other characids. It is presumed here 

 that the ectopterygoid bone grows anteriorly under the lower surface 

 of the palatines and that the dermal tooth-bearing bones under the 

 autopalatine are not dermopalatine elements that have fused to the 

 ectopterygoid but are simply anterior extensions of the ectopterygoid. 

 The striations and growth pattern of these tooth-bearing bones indi- 

 cate they are anterior extensions of the ectopterygoid. 



The accessory palatine of Sagemehl (1885, p. 95) that occurs in 

 Hoplias may be interpreted in two ways, either as a dermopalatine 

 or dental element that has not fused to the ectopterygoid or as an 

 autogenous, anterior piece of the ectopterygoid. Starks (1926, p. 

 161) maintains that the accessory palatine is homologous with the 

 dermopalatine of Amia. This problem cannot be resolved with the 

 information at hand. 



Probably the presence of teeth or dental plates associated with the 

 palatine, ectopterygoid, and mesopterygoid is a conservative featm-e 

 not retained in most other characids; in this respect the tooth pattern 

 of the Erythrininae would be more primitive than that of the other 

 subfamilies of living characids. If this is correct, the separation of 

 the Erythrininae from the rest of the characids might be suspected 

 then to have taken place when the characids had living representa- 

 tives much more primitive than those extant. In this connection, 

 the morphology and development of the first infraorbital and its 

 relationship to the antorbital in the Erythrininae and possible signifi- 

 cance of the infraorbital in the phylogeny of characids and Ostario- 

 physi should be investigated. 



Hyoid and branchial arches (fig. 8). — The hyoid arch of Nan- 

 nostomus and Poecilobrycon is not unlike that of the Characinae, and 

 the relative positions of the bones of the arches are the same. There 

 are two branchiostegal rays associated with the ceratohyal and one 

 with the epihyal. Members of the tribe Pyrrhulinini also have three 

 branchiostegal rays, while members of the tribe Lebiasinini have four 



