84 Journal New York Entomological Society. [Voi. v. 



of the clypeus, which is short and narrow, projecting from the epicra- 

 nium and shorter than the labrum. The latter is squarish, convex and 

 rounded at the end, which is thickened, with the edge entire, and pro- 

 vided with four chitinous acute tubercles, two on the edge and two be- 

 hind. There is a deep depression or pit between the labrum and the 

 insertion of the mandibles. The latter are short, very stout, thick, 

 conical, suddenly ending in an acute mucronate point or spine ; they 

 are short, situated far apart, and in my alcoholic specimen do not meet, 

 only reaching to the sides of the labrum. Maxillce unusually short, low, 

 obtuse, thick, terminating in two very minute corneous, low, obtuse tuber- 

 cles. Labium stout, short, thick, obtuse. Body long and slender, the 

 segments very regularly convex, scarcely thickened, more so in the 

 middle of the body than in the prothoracic segment, where it is most 

 marked in Andrena ; the lateral region distinct, the smaller portions 

 less marked than in the higher genera, an important distinction, especi- 

 ally observable in the lower genera of fossorial Hymenoptera, such as 

 Sphex, where there is scarcely any difference in shape between the pro- 

 thoracic and the abdominal segments. Beneath, the segments are 

 smooth, regularly convex, not thickened. The body is straightened out 

 more than usual, tapers unusually fast towards the end of the abdomen. 

 The last segment is much more rounded, more prominent or exserted, 

 more convex, and free from the rest of the body than usual, even in 

 Sphex. 



On a part of the head, and on the sides, and vertex, and on the 

 tergum are blackish pigment cells ; the thickened tergal portion not 

 ending in spinules as usual. The spiracles are large and more distinct 

 than usual in non-parasitic Apid larva;. 



In all respects the larva of this parasitic genus is lower, more de- 

 graded, much less differentiated than in the non-parasitic Apid larvae; 

 the lateral region is less marked ; the tuberculous thickenings nearly ob- 

 solete, and the whole body more attenuated, tapering rapidly towards 

 the head and end of the abdomen, and is more cylindrical. The head 

 is rather smaller in proportion than in the non-parasitic Apid larvae. 

 The very hard chitinous mandibles ; the almost obsolete maxillae, the 

 thickened, rounded, entire labrum, with its 4 tubercles, the minute, 

 faintly marked clypeus, the convex surface of the epicranium, not mesi- 

 ally depressed, with a subtriangular depression such as usually occur in 

 non-parasitic larvae of this family, are signs of degeneration, or at least 

 of adaptation to its parasitic habits, and slightly reminds us of the head 

 of dipterous larvae. The absence of spinules on the surface of the 

 tergum is noticeable. 



