Packard.] 142 [Nov. 19, 



Pennsylvania. It is closely similar to Calliphora vomitorla, but a little 

 longer. There are eleven divisions or lobules to the prothoracic stig- 

 mata, where in Calliphora vomitoria there are nine. The locomotive 

 spines are more acutely pointed. The anal spiracles are of the same 

 relative size as in Calliphora, but the openings are much longer and 

 narrower, and consequently farther apart, and the circular orifice in 

 the peritreme is wanting; in both genera the peritreme is round, 

 while in Musca it is somewhat hemispherical. The fleshy projections 

 around the spiracular depression, and the two fleshy prop-legs are the 

 same in the two genera, Sarcophaga and Calliphora, while the head 

 and its appendages present no differences. The only character by 

 which to distinguish the larva? of the two genera is in the form of 

 the stigmata. The mode of life, and of taking food, is identical in 

 the two; they differ but slightly in size, and here we have in the 

 preparatory state of two allied genera, no specific characters devel- 

 oped, the differential ones are generic in their nature. And yet the 

 imagines are very different, with a number of specific characters 

 separating them. 



The puparium (Fig. 8, ventral; 8 a, dorsal view, enlarged) is reg- 

 ularly cylindrical, at the fifth segment from the head beginning to 

 taper regularly towards the head, the anterior end being distinctly 

 pointed, the rudiments of the head and prothorax being small. Pos- 

 teriorly the body is much rounded, full and obtuse, with no spiracular 

 depression nor spines surrounding it, but the spiracles are situated 

 conspicuously like little buttons on the end. On the dorsal side of 

 the body is a single row of coarse granulations along the suture, be- 

 coming beneath double, with fine lines crossing and connected with 

 the granulations, the distance between the rows widening posteriorly. 

 Numerous granulations, rather finer than those anterior, surround the 

 rudiments of the prop-legs. A raised sharp prominent lateral ridge 

 extends on each side from the mesothoracie segment on to the first 

 abdominal. Prothoracic spiracles very minute, with usually six lob- 

 ules, and not extending beyond the mouth parts. The prop-legs are 

 represented by two oval flattened parallel contiguous tubercles, with 

 a rather remote and obscure area on each side. The anal spiracles 

 form black, round, flattened, button-like tubercles, the terminal seg- 

 ment being smooth and shiny, and regularly convex. 



Length, .20-. 2 7 inch. 



So remarkably similar is the puparium of Musca domestica to that 



