Dec. 1896.] Packard: Transformations of Hymenoptera. 157 
testaceous or chitinous line, opposite and just within the lower end of 
which are situated the antennal rudiments, situated in a round depres¬ 
sion. Supraclypeal piece obscurely marked at the base. Clypeus sub- 
trapezoidal, angular in the middle on each side ; twice as broad as long ; 
base and front edge transverse, the front edge slightly concave, exserted 
so as partially to envelop the base of the mandibles. Labrum very free, 
exserted and overlapping the mandibles; more than twice as broad as 
long, bilobate, the corners rounded, the front edge excavated; thin, 
translucent. Mandibles short, twice as long as broad at base, triden- 
tate, the mesial tooth largest, the inner smallest. Maxillae rather long 
and slender. Rudiments of the palpi acute, longer and more pointed 
than usual. 'Labium a little wider than usual, the rudiments of the 
labial palpi acute. Body long cylindrical, the segments of uniform 
size and shape, not thickened much behind, but still as much so as in 
the larva of Megachile , for instance, and in this respect very different 
from Crabronid and Pompilid larvae. The pleural region is not promi¬ 
nent. The body is very cylindrical; the tip broad obtuse, the terminal 
tergites and sternites broad and flat, together forming an orbicular area, 
very different from the exserted prominent knob-like ending of the 
larva of Pompilus . 
It differs from the larva of Pompilus in the short curvilinear tes¬ 
taceous line, in the short broadly trapezoidal clypeus and the distinct 
exserted labrum. The mandibles differ from those of Pompilus in be¬ 
ing tridentate and twice as long. The front edges of the segments 
are thickened, but not so convex as in Pompilus , giving a serrate ap¬ 
pearance to the body. Tip rounded, full, not nearly so acute as in 
Pompilus. The larvae of the two genera differ greatly; indeed, more 
than one would suspect, considering that they are representatives of two 
allied families. 
Pelopaeus cementarius ( Drury) (flavipes Fabrl). 
Pupa. —The pupa of Pelopceus differs from that of Polisles and 
Vespa in the head being raised more from the pectus. The palpi are 
visible along their whole length. The legs are much longer, and the 
pedicel is of the same shape as in the adult. The head is much as in 
the imago. The mandibles long, slender, curved, covering the base of 
the maxillae and lingua. The scape of the antennae is oblique; the 
flagellum reaches to the posterior coxae, resting between the two anterior 
pairs. The maxillae are slender, not reaching to the entire labium. Ot 
the rhabdites or blades of the ovipositor, only one pair is visible; the 
