162 Journal New York Entomological Society. [Voi. iv. 



nients convex, those of the thorax broad, regularly convex, smooth, not 

 thickened posteriorly; quite different from those of the abdomen. The 

 abdominal segments shorter posteriorly above than the thoracic ones. 

 The posterior portion of the segment thickened so as to form a rounded 

 tubercle, which is very prominent and distinct when the body is much 

 curved. This portion is thickened ; the tuberculous portion is much 

 smaller in proportion to the rest of the segment than usual in Apidae. 

 The tip is quite extensible, subacute, terminating in a small knob-like 

 portion. Genitals not apparent, the skin being too thick. A few sparse 

 long hairs over the body, in which respect this genus differs from those 

 of the other families, and it differs in its elongated extensible tip, though 

 it is probable that this part became contracted in alcohol ; when con- 

 tracted, the terminal segment is rather square, not being rounded at the 

 tip. Length of body .25 inch. 



The larva burrows, in the dust made by the larva of an .Egeria in 

 the pith of the Spircea, spinning little thin silken cocoons, half a dozen 

 of them occurring in a space of the stem an inch long, lying loose in the 

 galleries, some lying across the stem, and others lengthwise. The 

 cocoon is very thin and slight compared with that of Crabro sex-rnacu- 

 lata, being composed of only a few silken threads. Found April i8th'. 



Pupa. — 9. The middle joint of the antennal scape is bent at right 

 angles to the flagellum, the third joint being continuous with the flagel- 

 lum, while in Pelopants flavipcs it is more oblique, as the front of the 

 head is longer and more horizontal, while in Rhopalum it is at right 

 angles to the longitudinal axis of the body. The head is more vertical, 

 less flattened on the pectus of the thorax. Mandibles thick and stout, 

 convex, much more so than in Pelopccus. The antennae do not quite 

 reach to second pair of trochanters ; in Pelopcetis, they reach beyond 

 the third pair; they also reach the tip of the maxillary palpi, which in 

 Pelopccus reach half their length. They rest close to each other along 

 the median line of the body. The maxillary palpi are straight, not 

 slightly elbowed near the base ; they reach to the tip of the 

 antennae; the labial palpi are proportionately longer, reaching ijearer 

 the tip of the maxillary pair than in Pdopceiis, and less elbowed or 

 angulated at tip. The anterior tarsi end just before the middle trochan- 

 ters ; the middle tarsi terminate near the end of the pedicel of the ab- 

 domen, and the third tarsi end near the middle of the third abdominal 

 segment. Tip of abdomen with the terminal tergite very acute, elon- 

 gated, extending beyond the ovipositor; the last sternite is oblong, 

 flanked on each side by two cylindrical pieces. On the head between 



