386 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



apparently the development of hind coxal spurs, found 

 to be small and inconspicuous in lovetti but stronger in 

 coxalis and rita. 



A new development occurs in all the species following 

 these In pisticoides the venter of the third segment is 

 carinate at the end ; in auripleura the venter of the fourth 

 segment also is carinate at the immediate base, but 

 here the carina of the fourth segment is sometimes very 

 slight and rugose while in carinata it is well-marked. 



In the species which follow the hind trochanteral 

 process is much shorter with the end rounded. With 

 the development of the ventral spurs there is, also, a 

 marked tendency for the middle coxal processes to 

 disappear. 



No one seems ever to have understood the reason for 

 the development of these remarkable processes on the 

 legs. It is possible that they serve some purpose during 

 copulation. Possibly the knobs on the end of the tro- 

 chanteral processes fit into the abdomen of the female 

 at its base, or into the sides of the scutellum, but they 

 are rather close together for the latter purpose. 



However, with the development of the ventral ab- 

 dominal spurs, it appears that the use for the trochan- 

 teral processes is disappearing. It would therefore seem 

 that the two must serve the same purpose. If such is 

 the case, a most interesting question arises: Why 

 should it be necessary to develop the coxal and tro- 

 chanteral processes in order to later develop the ventral 

 spurs? It would seem that the development of the 

 ventral spurs should have occurred naturally without 

 the intervening development of the processes, but the 

 evidence indicates that this was not the case. It is 

 also remarkable that so far all the species bearing the 

 ventral spurs occur in the vicinity of the Great Lakes. 

 That such species may be developed on the Pacific 

 Coast is to be expected because of the presence there 

 of two species, albipleura and auripleura, which fall 

 immediately below the spur bearing forms. It will be 

 interesting to watch the development in this region and 



