THE ROBBER-FLY. 255 



is guilty of seizing and devouring honey-bees. The larvae had 

 made their burrows in the loose and shifting beach sand by the 

 seashore, in which grew scattered blades of a grass on the roots 

 of which the larv£e probably fed. The insects had all passed, at 

 the date they were observed, (July 18th,) either into the pupa 

 state, or were flying about the beach, having 

 undergone their transformations. The chrys- 

 alids (fig. 4, front and side view,) were observed 

 protruding about an eighth of an inch from the 

 edge of the hole. 



The head and thorax are gathered into a 

 mass very distinct from the abdomen, which is 

 unusually slender, cylindric and rather long. 

 The head is short and small, and considerably " fig. 4. 

 narrower than the thorax. On the vertex are two large curved 

 spines, and on each side below is a large oblique tubercle, like a 

 deer's horn, and giving rise to three stout spines like those on 

 the vertex. Below, and on each side of the front, is a little pit. 

 The mouth-parts are well developed, the labrum being square 

 and nearly one-half as long as the mandibles, which are large 

 and reach nearly to the end of the labrum, which is broad and 

 rounded at the end. The legs are convex and not so much 

 merged in with the integument as usual ; the second pair are 

 partially overlapped by the wings, the ends of the third pair 

 projecting beyond the rather small wing-cases. The whole mass 

 of appendages is raised from the base of the abdomen, and 

 reaches to the front edge of the third abdominal segment. On 

 the side, near the base of the legs, is a tubercle, giving rise to 

 two spines of unequal length. Just above, and placed a little 

 anteriorly, is the large, round prothoracic spiracle. There are 

 seven pairs of abdominal spiracles. The abdomen is long, cylin- 

 drical, a little curved, gradually tapering to the blunt tip ; the 

 segments are rather convex, and the sutures wide and deeply 

 cut ; along the side is a large convex ridge on which the spir- 

 acles are situated. Near the hind edge of each segment is a 

 row of long, stout spines, of unequal length, surrounding the 

 body, many of them being one-half as long as the segment it- 

 self. At the base of the terminal joint is an impressed trian- 

 gular area, and at the tip two rather long, straight spines arising 

 from slender tubercles ; beneath, are two pairs of small tuber- 



