HYMENOPTERA 893 



Argidae; but these are not provided with hooks as are the prolegs of 

 caterpillars. 



A striking feature of the larvag of this suborder is the possession 

 of a pair of ocelli, one on each side, which in their position and in 

 their structure agree with the ocelli of adult insects, that is, they are 

 primary ocelli. This characteristic distinguishes these larvae from 

 the larvce of Lepidoptera, which have only adaptive ocelli, usually 

 several on each side (See page 136). 



A classification of the larvae of this suborder was published by 

 Yuasa ('22). 



TABLE FOR DETERMINING THE FAMILIES OF THE 

 CHALASTOGASTRA 



A. Front wings with three marginal cells, both vein r and R2 being present; the 

 basal segments of the flagellum are consolidated, thus forming what appears to 

 be a very long third segment, and the remaining segments are small, p. 894. 



Xyelid^ 



AA. Front wings with the free part of vein R2 always wanting; antennae with 

 three or more segments, third segment never as long as all the following seg- 

 ments together; if the third segment be long, antennae consisting of only 

 three segments. 

 B. Front wings with subcosta present as a distinct longitudinal vein. p. 895. 



Pamphiliid^ 



BB. Front wings with subcosta absent; rarely it is present as a pale, very in- 

 distinct line, closely appressed to vein R -|- M, or vein Sci may be present as a 

 transverse vein. 



C. Radial cross-vein (r) of the front wings received by the 2nd submarginal 



cell (Rs) or if it is absent or the 2nd and 3rd submarginal cells united 



(R4 united with Rj), then the anterior tibiae have a single apical spur. 



D. Front wings with the cross-vein m-cu subequal in length to the first 



section of the free part of media. 



E. Vein Sci absent in the front wings; the last abdominal segment 

 bears a more or less horn-like prolongation; maxillary palpi one- 

 segmented; labial palpi two- or three-segmented, the last segment 

 enlarged and bearing a large sensory cup, the first segment not 



elongate, p. 896 Siricid^ 



EE. Vein Sci present; last abdominal segment without horn-like pro- 

 longation; maxillary palpi four-segmented; labial palpi three-seg- 

 mented, the last without a sense-cup, the first elongate, p. 897. . . . 



XlPHYDRIID^ 



DD. Front wings with the cross- vein m-cu joined to vein M at or near its 



separation from vein R. p. 898 Cephid^ 



CO. Radial cross-vein (r) of the front wings received by the 3rd or 4th 

 submarginal cell (cell R4 or R3) or wanting; anterior tibiae always with 

 two apical spurs. 



D. Abdomen with distinct pleural sclerites, bearing the spiracles; an- 

 tennae clavate. p. 900 CiMBiciDyE 



DD. Abdomen without separate pleural sclerites; antennae not clavate in 

 North American forms. 

 E. Scutellum with a distinct apical plate, the post-tergite; posterior 



coxae contiguous or nearly so. p. 900 Tenthredinid^ 



EE. Scutellum without a post-tergite; posterior coxae often widely 

 separated, p. 902 Argidae 



