Fossorial ITymenoptera of North America. 4D 



1 abits bear a close resemblance to each otber; and it need not be said 

 that one necessarily mimics the other. Before dogmatizing: on this 

 subject we must wait for further information concerning the habits of 

 these, next to the Apida?, most interesting of all hymenoptera, and 

 see how intimately structure is correlated with differences of habits. 



PlllLANTHINiE, Dahlbom. 



ITrnd short and broad, beinc a little more than a third as broad as 

 long; somewhat oblong transversely, with the angles rounded much 

 more than in Pemphredinx and Crabronwse. Eyes narrow, oval, often 

 indented in Phflanthus : on the vertex reaching the middle (transversely) 

 of the vertex, and sometimes passing a little beyond the middle; upon 

 the vertex the distance apart of the eyes varies somewhat, as in Cerceris 

 they closely approach each other. The vertex is always convex, and a 

 little elevated, with the ocelli placed uniformly in an equilateral trian- 

 gle a little below the summit of the vertex which rises a little up be- 

 hind them. The front is flat and square, widening a little towards the 

 insertion of the jaws, since the eyes approach each other a little above. 

 The insertion of the antenna; varies both in the distance apart of their 

 bases, though it is always considerable, and their distance from the 

 front edge of the clypeus. This is generally above the middle line of 

 the front. The antennae themselves are rather long; the second joint 

 not appressed to the front, short, and very thick, while the succeeding 

 joints are rather long, often thickening towards the tip. The clypeus 

 is as long as broad, subtrapezoidal. 



This group, which is so clearly limited from its three neighboring 

 groups by its broad square front, is further still more circumscribed by 

 the two " lateral lobes" of the clypeus, which are here somewhat square 

 and much larger than in the other groups; and by the piece on each 

 side of the antenna?. Moreover, the group is rendered still more tren- 

 chant by the raised piece, often carinated between, and which widens 

 below the insertion of the antenna?, which is seen so clearly in Cerceris 

 deserta. Moreover the front and clypeal region are naked, which sepa- 

 rates them from the two other groups of the family. 



Thorax may be said to be oblong sub-cylindrical, being a little pro- 

 duced behind, since the meta-scutellum is less inclined than in the 

 Crabro, and thus less globular than in that group. The prothorax is 

 more continuous with the forward and lateral slope of the meso-thorax 

 than in Crabronimo. Meso-seutellum very like that of Crabronina? but 

 shorter in the main than broad, and it is besides broader behind, next to 

 the scutellum which is' longer than in Crabro, as is the enclosure of the 



PROi EEDINGS ent. sue. piiilad. may, ISCfi, 



