296 



KELLOGG AND BELL 



In the males, 14 individuals had three complete red-centered 

 ocelli on the under side of the hind wings, while two individuals 

 had but two such ocelli. 



In the six females the red-centered ocelli on the upper side of 

 the hind wings varied in number from two to four. 



These two cases are only included as examples of a condi- 

 tion familiar to all collectors and systematic students of moths 

 and butterflies, namely, the constant presence of considerable 

 variations in the wing-patterns. As these patterns are certainly 

 to be looked on as blastogenic characters, and as positive use- 

 fulness must certainly be presumed in connection with so spec- 



\ 



FIG. 60. 



ialized a character as the color-pattern of the Lepidoptera, the 

 evolutionary or species-forming factors find plenty of truly 

 blastogenic variations in the group for working material. 



Variation in Number of Tarsal Segments of Periplaneta 

 americana (the American Cockroach). A lot of 118 individ- 

 uals (74 males, 39 females, 5 broken) of Periplaneta americana, 

 the American cockroach, collected in December, 1894, in La 

 Paz, Mexico, was examined for variation in the number of seg- 

 ments in the tarsi of the various feet (see fig. 60). Fourteen 

 classes were found as follows : 



