THE AMERICAN TETRAGONOPTERINAE. 51 



q. Premaxillary teeth in two series. 



r. Second suborbital not in contact with the preopercle below, 

 or with 5 teeth in the inner series of the premaxillary. 

 8. Lateral line incomplete. See Psellogrammus. 



/. Few teeth if any near the upper angle of the premaxillary. 



u. An adipose fin 10. Hyphessobrycon Durbin. 



uu. No adipose fin 11. Ease-mania Ellis. 



It. Maxillary with teeth along its entire edge. 



v. Anterior teeth of the lower jaw all alike, tricuspid; 



anterior pair of premaxillary teeth little larger 



than the rest ... 12. Hollandichthys Eigenmann. 



w>. Lateral teeth of lower jaw enlarged, the fourth 



usually largest; middle teeth of premaxillary 



much enlarged 13. Pseudochalceus Kner. 



(vvv. Anterior teeth of the lower jaw all alike, multi- 

 cuspid ; caudal scaled . . 8. Pristella Eigenmann) . 

 ss. Lateral line complete. 



w. Teeth of the sides of the lower jaw more or less 

 abruptly minute, 

 x. Maxillary-premaxillary border angulated 

 where they meet. 

 y. Scales cycloid. 



14. Astyanax Baird & Girard. 



(z. Predorsal line scaled Astyanax. 



zz. Predorsal line at least partly naked. 



Poecilurichthys Gill). 

 yy. Scales ctenoid at least on breast; anal long, 

 39-47, predorsal line scaled. 

 A. Lateral line complete. 



15. Ctenobrycon Eigenmann. 

 A A. Lateral line stuttering. 



16. Psellogrammus Eigenmann. 

 xx. Maxillary-premaxillary border a continuous 

 curve, half as long as the head. 



17. Astyanacinus Eigenmann. 

 ww. Teeth of the lower jaw all alike in character 

 and regularly graduate from in front to the 

 last tooth on the sides; two teeth in the 

 front row of the premaxillary on each side; 

 teeth of the second row multicuspid incisors 

 with a contracted base, their anterior and 

 posterior surfaces alike, convex, without dis- 

 tinct ridges. ... 18. Deuterodon Eigenmann. 

 ivww. Teeth of the lower jaw similar, the lateral ones 

 much wider than the anterior ones; maxil- 

 lary with two very broad incisors whose 

 combined width is about half the length of 

 the maxillary .... 19. Landonia Eigenmann. 

 rr. Second suborbital in contact with the lower limb of the pre- 

 opercle; four teeth in the inner series of the premaxillary. 



