June, 1S97.] Packard : Transformations of Hymenoptera. 83 



the clypeus is a dark, corneous, minute, stout, acute spine. (The use of 

 this process is unknown ; it is not present in the larva of Sphex, and is 

 an interesting larval structure.) The mandibles are long, narrow, in- 

 curved, the tip very acute and rather long. The maxillae are cylin- 

 drical, stout, short and thick, obtuse, ending in a corneous, black, low, 

 obtuse tip. The labium is short, divided a little at the end, and in the 

 middle into two short, obtuse tubercles. 



Compared with the larva of Bomhiis the vertex is not so rounded and 

 smooth, while the lateral eye-pieces are remote and more bulging in front, 

 leaving a broad, depressed mesial interspace ; the distinction so marked 

 jn Bombus between the clypeus and labrum is in Afidrena almost an- 

 nulled, the labrum in Andrena being at first easily mistaken for an an- 

 terior portion of the clypeus, until after comparison has been made ; its 

 edge differs from that of Bombus and most other hymenopterous larvae 

 in being square, entire and much longer, while the trophi, /. e,, the max- 

 illae and labium, are in Androia a little shorter, less produced beyond 

 the mandibles and labrum. In Andrena and Halictus the segments are 

 much more convex and angular, more tuberculous, while the last ab- 

 dominal segment is broader, more transverse than in Bombus, where it is 

 orbicular. 



Fig. 7. Andrena vicina, pupa, enlarged nearly three times. (Emerton del.^ 



Nomada (probably imbricata Smith). 



Larva. — The head is much smaller in proportion to the rest of the 

 body than in Andrena, smoother and rounder, somewhat flattened, seen 

 from in front somewhat square, with the angles rounded off; the eye- 

 pieces not full convex as usual, but continuous with the middle of the 

 front, which is not depressed mesially. Two black chitinous tubercles 

 situated rather far apart on each side of the epicranium in a line with 

 the insertion of the mandibles, being much farther apart than the sides 



