42 



THE AMERICAN CHARACIDAE. 



hausia lepidurus and the species of Creatochanes the middle rays and upper 

 caudal lobes are black. In Astyanax lineatus and A. steindachneri, in Moenk- 

 hausia latissimus, and in Hollandichthys and Pseudochalceus dark lines follow 

 the spaces between successive rows of scales. The dorsal and anal are marked 

 with black in a few species. 



The points of greatest variability within a genus are: — 



1. The depth and all that this carried with it, length of occipital process, rows of scales, 

 number of rays of anal. 2. The size of the mouth and the dentition. 3. The degree of 

 armature of the cheek. 4. The scaling of the caudal, anal, predorsal, and preventral areas. 

 5. The degree of development of the lateral line. 



Contrasted Generic Characters. 



The following mutually exclusive characters are found variously combined 

 in different genera. The characters appearing in the largest number of genera 

 are given in the first column. 



A. Caudal fin naked. a. 



B. Lateral line complete. b. 



C. Maxillary with few teeth or none. c. 

 V. Premaxillary teeth in two series. d. 



E. Cheeks partly naked. e. 



F. Anterior edge of maxillary a simple /. 



curve. 



G. Predorsal line scaled. g. 

 H. Teeth of the sides of the dentary h. 



abruptly smaller. 

 I. Premaxillary meeting the maxillary of an i. 



angle. 



J. Scales entire. j- 



3- 



K. Anal naked except at the base. k. 



L. Lateral line nearly straight. /. 



M. Preventral area with normal scales. m. 



N. Gill-rakers setiform. n. 



0. Adipose fin present. o. 



P. Origin of anal behind origin of dorsal. p. 



Q. Caudal without glandular scales. q. 



Caudal scaled. 

 Lateral line incomplete. 

 Maxillary with teeth along its entire edge. 

 Premaxillary teeth in three series. 

 Cheeks entirely covered by the third sub- 

 orbital. 

 Anterior edge of maxillary sigmoid. 



Predorsal line naked. 



Teeth of the sides of the dentary gradu- 

 ated. 



Maxillary-premaxillary border a simple 

 curve. 



Scales ctenoid. 



Scales crenate. 



Anal scaled to near its tip. 



Lateral line sharply decurred in front. 



Preventral area with paired scales. 



Gill-rakers lanceolate. 



Adipose fin wanting. 



Origin of anal under or in front of origin 

 of dorsal. 



Caudal with glandular scales. 



The characters appearing in the larger number of genera and given in the 

 first column are all found in Astyanax, which may for that reason, be the central, 



