2 PKOCEEDINGS OF THE NATIONAL MUSEUM vol. 70 



TERMINOLOGY 



Except for the terms used in connection with tlie male genital 

 structures, which have not been used by other authors very exten- 

 sively in the interpretation of relationships in this group, the ter- 

 minology employed does not depart from that in general use among 

 the students of the aculeate Hymenoptera, and need not be defined in 

 detail here. The explanation of the plates which accompany this 

 paper will doubtless give sufficient information. 



MALE GENITALIA 



The terminology used to designate the various genital structures 

 seems to be in a state of confusion, and very little has been done to 

 establish a uniform system of nomenclatwre throughout the different 

 groups. The terms used in this paper are only tentative, and further 

 study may show the desirability of changes. The parts of the genital 

 structures in the genus Sceliphron have provisionally been desig- 

 nated as follows: (1) Basal ring (cardo), (2) claspers, (3) uncus, 

 and (4) combined volsellae and sagittae. 



The hasal ring is narrow throughout, and especially so on the 

 dorsal side. It surrounds the basal part of the genitalia. 



The claspers are long and stout, and almost entirely enclose the 

 other parts above. Dorsally and ventrally at the base, arms project 

 inward; the dorsal arms seem to just about meet, and the ventral 

 ones overlap. Near the tips of the claspers are a few scattered hairs. 



Articulating with the dorsal basal arms of the claspers is a 

 structure which I have tentatively termed the uncus, consisting of 

 two structures loosely connected by a membrane three-fourths of 

 their length. The distal portions, which are not connected by this 

 membrane, are more heavily chitinized and are more or less curved 

 or hook-shaped. Structures similar to this uncus in some Hymenop- 

 tera are termed by Radoskowski the " crotchets. " 



Ventral to the uncus, and arising near the ventral basal arms 

 of the claspers is a structure, presumably consisting of the volsellae 

 and sagittae, which have become more or less fused. Taken together, 

 they are similar to a structure which Radoskowski calls the 

 " bouclier ". It consists of a large basal portion divided except at 

 the very base, possibly representing the volsell-ae which have become 

 partially united, and of two smaller structures fused to the inner 

 distal edges of the volsellae and possibly representing the sagittae. 



The genital structures except the claspers are concealed ventrally 

 by the subtriangular venter of the eighth abdominal segment, which 

 is partly telescoped under the venter of the seventh segment. 



The genitalia have proved useful in determining specific relation- 

 ships. Thus genitalia of the different forms here placed under 



