296 THE AMERICAN CHARACIDAE. 



The following table (p. 297) shows the variation of the species in the 

 number of anal rays and scales in the lateral line in different localities. The 

 numbers in the different Unes indicate the niunber of specimens from the particu^ 

 lar locality possessing the character indicated at the head of the column. 



In southeastern Brazil, Astyanax fasciatus is found associated in the same 

 rivers with A. taeniatus and its variations and with A. scahripinnis and its 

 varieties. While in any particular stream, it is comparatively easy to dis- 

 tinguish between them each undergoes so many modifications in different rivers 

 that it is not possible to give a clear definition that will distingmsh the species 

 when specimens from all the rivers are considered. Astyanax fasciatus is a long 

 analed, slender, sharp-snouted species that about Rio de Janeiro grades in the 

 number of its anal rays and in its shape perfectly into A . taeniatus which on an 

 average is a shorter analed, deeper, sharp-snouted species. South of Rio Janeiro 

 it grades into A. eigenmanniorum the still deeper substitute of A. taeniatus of 

 the northern rivers. Astyanax taeniatus in its turn grades into A. scahripinnis, 

 a slender, short-analed, heavy-jawed species. The latter and its varieties are 

 always readily distinguishable from A. fasciatus; but A. taeniatus may some- 

 times be taken for A. scahripinnis on the one hand, or for A. fasciatus on the 

 other. Liitken figm'ed both A. scahripinnis and A. taeniatus as his A. scahri- 

 pinnis rivularis. Jenyns in the original descriptions of A. taeniatus and A. 

 scahripinnis recognizes the former as an intermediate form. 



The matter is comphcated by the fact that different river systems have 

 different varieties of the several species and by the fact that if we imagine A. 

 fasciatus, A. taeniatus, and A. scahripinnis to form a triangle A. intermedius 

 would occupy the center of it. 



The maze was disentangled with the Thayer material. Three years later, 

 after the Thayer material had been returned, the large collections of Haseman 

 became available for study. This separate study has had its advantages and 

 disadvantages. I confess that after three years I had to approach the question 

 of the species practically ah initio. I think a reduction in the number of accepted 

 species would have been justified. It is, however, always easier to confuse facts 

 than to disentangle them and very few changes have been made in the con- 

 clusion first reached. 



