16 MEMOIRS OF THE CARNEGIE MUSEUM. 



j. Lateral line with but few pores; cheeks behind the eye mostly naked. 



k. Caudal partly scaled H. Aphyodite^ Eigenmann. 



kk. Caudal naked. 



I. Pseudotympanum conspicuous; no teeth on maxillary; interorbital 



very convex; frontal fontanel moderate; premaxillary with five, 

 to seven mostly conical teeth, similar to Parecbasis; the lateral 

 Une incomplete 12. Macrosobrycon Eigenmann. 



II. No pseudotympanum; maxillary with two to twenty teeth; four 



to eight tricuspid teeth in front part of mandible, minute teeth on 

 side; fontanels very large.. . . 13. Megalamphodus Eigenmann. 

 jj. Lateral Une extending to within four scales of the caudal. Twenty-five 

 or more teeth on each ramus of the mandible; twelve teeth on the maxil- 

 lary; frontal fontanel moderate; cheeks behind as well as below the eye 

 covered; mouth moderate; subfusiform. 



14. Microschemobrycon Eigenmann. 

 gg. Teeth heavy, four on the premaxillary; mouth minute; maxillary not reaching to below 

 eye, with one or two teeth; origin of dorsal equidistant from snout and caudal; no 

 pseudotympanum; tlu'ee postorbitals covering nearly the entire postorbital area. 



15. Oligobrycon Eigenmann. 

 cc. Teeth in part at least with five or more lobes. 



m. Sides of teeth nearly parallel, those of the upper jaw narrow, with a prominent median cusp and 

 one or two minute cusps on each side, about ten teeth in each premaxillary; mandible with 

 tliree- to five-lobed teeth, much expanded at tip, the tln-ee middle lobes equal in size, blunt, 

 those of successive teeth in contact, forming a continuous cutting edge, the lateral lobes 

 excessively minute; mouth large, cheeks partly naked; frontal fontanel very short; no pseudo- 

 tympanum; interhfemals normal; lateral line incomplete. .. 16. Aphyocheirodon Eigenmann. 

 mm. Teeth with five or more points, tops of those of the lower jaw not forming a continuous cutting 

 edge, 

 n. Lateral Une incomplete. 



0. Male with a lobe of large scales extending along the base of the middle caudal rays; all 

 but three or four last anal rays of the male with hooks; interhaemals of the caudal 

 peduncle weak; mouth minute; maxillary barely reaching to below eye; second sub- 

 orbital covering the entire cheek; postorbitals very weak; no pseudotympanum; 



frontal fontanel moderate 17. Compsura Eigeimiarm. 



00. Caudal of male without a median lobe of scales. 



p. InterhiEmals of the caudal peduncle of the male, next the caudal, feeble; no pseudo- 

 tympanum; teeth heavy, one on the maxillary; third suborbital with a naked 



border 18. Mixobrycon Eigenmann. 



pp. Interha;mals of the caudal peduncle, especially in the male, prominent, spine-like, 

 protruding; a conspicuous pseudotympanum; one to three teeth on the maxillary; 

 teeth of upper and lower jaw similar, with five or more points. 



19. Cheirodon Girard. 

 nn. Lateral line complete; interhsemals feeble, not projecting; maxillary with a few broad-tipped 

 teeth; second suborbital in contact with the preopercle below. 

 ' Aphyodite, Macropsobrycon, and some of the species of Megalamphodus are very similar. 



