HO ( I T 1 1 A M E I ; I CAN FISH I'^S 



25 



readily point out characters that have uiuloubtedly n risen inde- 

 pendently in different genera. Very fre(juently tlie jjrotM'ss is 

 going on at present. In some rare cases, where a species is widely 

 distributed, it may be in a state of staible e(iuilibrium in oru; place, 

 or over most of its territory ; while at some definite locality it is 

 changing, or, to make the statement conservative, it is unstable. 

 See Ctcnohrycon haiuxwelUwnus below. 



Assuming that the more frequent condition is the original 

 one, there are enumerated below specific instances of a few of the 

 cases where independently one character has changed to another. 



The character that has been changed more fretjuently than 

 any other is the lateral line. This has become incomplete re- 

 peatedly; and it is becoming incomplete in many instances at the 

 present, unless we consider the instability itself a specific charac- 

 ter of the species showing the change. Similar changes have 

 taken place in other Gharacins of America and Africa and in Cyp- 

 rinids. 



Following is a table of genera with a complete lateral line and 

 their relatives with an incomplete line : 



(Jcneru with 

 lateral line complete. 

 Tetragoiiopterus 

 EiitoiiiO'lepis 

 Moenkliausici 



Astyaiiax 

 KiiocUis 

 Markiana 

 Gymiiocorynibns 

 Cteiiobrycon 

 Creatoc'lianes 

 . Brycoiiops 

 C'i'eagnitns 

 IMabiiia 

 Microgenys 

 Brycoiiaiiiericus 

 Zygogaster 

 Ceratobraiicliia 

 Lancloiiia 

 Dentei'odoii 

 ITeiiiilirycon 

 l*heiiacogaster 

 Scissor 

 Heiiochiliis 

 Psalidoclon 



Genera tritJi lateral line ineonipletc 



iiuiie. 

 none. 



Heniigraiiimus (further changed into Pristella and 



Thayeria). 

 Hyphessobrycon (into Haseniania). 

 none, 

 none, 

 none. 



Pselhjgrannnns. 



P>rycochandus. 



none. 



none. 



none. 



none. 



none. 



none. 



none. 



none. 



none. 



Holh-mdiclithys and Psendochalcens. 



Vesica trns. 



none. 



none. 



none. 



