46 Annals Entomological Society of America [Vol. Ill, 



also known as the "sternal spatula" or "anchor process," an 

 organ said to be peculiar to the Ccciclomyidac. This is a brownish 

 chitinizcd ])rocess varyinj.; somewhat in shape, but usually widest 

 at the extremities, slightly constricted at or near its middle and 

 at the caudal end, and somewhat incised anteriorly where a small 

 portion of it i)rojects beyond a transverse fold. The caudal 

 extremity is concealed under the posterior fold of segment I. 

 The anterior incised portion of the spatula is somewhat scooped 

 out, and the more heavily chitinizcd central axis sends out a 

 ridge on either side of this depression. Otherwise the whole piece 

 may be quite uniformly chitinizcd. A lateral view of this organ 

 shows that it follows the curved outline of that part of the seg- 

 ment in which it lies. 



The use or the homology of the "breastbone" has been a sub- 

 ject of some speculation. Giard (8) says that some of these 

 Cecidomyid lar\'ae have the power of leaping, using their well 

 developed spatula and terminal corneus papillae for this process, 

 and in this wise : the larva bends itself almost into a circle, and 

 hooking together the breastbone and papillae breaks the con- 

 nection thus formed and the spring occurs. In the species re- 

 ferred to by Giard however the spatula is well muscled, strongly 

 chitinizcd, projects well externally, and the corneus papillae are 

 developed. The advantage gained by this faculty of leaping is. 

 according to Giard. the assurance of the dissemination of the 

 species, which in turn insures an abundant food-supply and 

 therefore the successful perpetuation of the species. The larvae 

 of Diplosis loti and jacobeae, cited as examples by him as having 

 this leaping power, are gregarious and would not leave enough 

 food for their descendants if they were not thus motile. This 

 theory does not seem adequate inasmuch as the adults look after 

 the food-supply for their i)rogeny, and being acti\'e and winged, 

 would have no difficulty in finding another suitable plant on 

 which to oviposit. The motile habits of the larva brought 

 into play just before pupation would indicate a search on the 

 part of the insect for a proper place for puliation, the inijia being 

 formed underground and probabh' at no great distance from the 

 abandoned food-plant. In C. rcsinicoloidcs the spatula is not 

 well developed, projects but slightly anteriorly, and the posterior 

 corneus pa])illae arc absent, also as the insect lives both in the 

 larval and pupal stages in pitch, the breastbone could hardly be 

 used as a locomotor organ. In fact it does not appear to be con- 



