84 THE AMERICAN CHARACIDAE. 



In the specimens with the lateral line imperfect the scales along the lateral 

 line series are as follows, the scales with pores being in italics: — ' 



Corumba 10 + 15; 8 + 16; Puerto Suarez 8 + 14; Caceres 22 + 1 + 49; 

 22 + 3+3; 8 + 17; 10 + 15; 9 + 16; 10 + 16; 9 + 16; 8 + 17; Rio 

 Boa Ventura 8 + 16; 10 + 16; 10 + 1Q; 3 + 1 + 8 + 16; 9+ 17; Rio 

 Sapon 6+18; 19+2+2; 12 + 1+3; Cachoeira 12+2+9 + 1; 14 + 

 2 or 3 + 9; 15 + 1+8 + 1; Rio Tiete" 13 + 11 and two small ones with 

 short lateral line; Caceguy 15 + 3+7 + 1; Arequa 8 + 16; 10 + 15; 10 + 

 15; Rio Jauru 11 + 14; San Joaquin 8 + 17; 10 + 17 (and three others with 

 an incomplete line). In the other specimens the lateral line is complete. 



Summarizing the data we find that there are two groups of specimens. 

 The first consist of one with six scales with pores, seven with seven scales, three 

 with nine scales, eight with ten scales, one with eleven and one with thirteen 

 scales with pores. In each of these cases the remaining scales of the series are 

 without pores. 



To this series also belongs one specimen in which the lateral line series con- 

 sists of three pores, one scale without a pore, three with pores and sixteen with- 

 out pores. This is evidently a modification of seven scales with pores and 

 sixteen without pores. Most of these come from the Paraguay and Parana 

 Basins and represent M. australe. 



In the remainder of those enumerated the modifications are of another sort. 

 The lateral fine reaches the caudal or within one scale of the caudal, but is 

 interrupted, skipping one, two, or three scales. All of these with the exception 

 of two from Caceres came from southeastern Brazil and represent M. sanctae 

 filomenae. It is scarcely possible that they indicate the road from the com- 

 plete lateral line to the incomplete, for in those with the incomplete lateral line 

 the number of scales at the beginning of the line with pores is usually eight to 

 ten, and specimens having this character occur at the same locality with others 

 with complete lateral lines. In those with the interrupted lateral line there 

 are from fourteen to twenty-two scales at the beginning of the line with pores, 

 and while these also occur along with others with complete lateral line, they 

 in general are found in other river basins in an area geographically widely sepa- 

 rated from the area in which those with incomplete lateral lines occur. 



There seem to be variations (constantly occurring or mutations) in two 

 different directions, one of these directions leads to Hemigrammus which is a 



1 1 am indebted to Mrs. Marion Durbin Ellis for the examination of these specimens in connection 

 with her study of Hemigrammus and Hypheasobrycon. 



