68 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 50 



LIST OF THE SPECIES OF WHICH WING SECTIONS WERE 



STUDIED 



(Of the species printed in italics paraffine sections, permitting a closer study- 

 under higher powers, were made. Of the others, only thicker celloidin 

 sections were studied.) 



Tenthredinidse : Tenthrcdo mcsomclccna L,., Sirex gigas L. 

 Ichneumonidse : Exetastes fornicator Grav., Campoplex aculeator Holmgr., 

 Dyspetes praerogator Thorns., Henicospilus ramidulus 

 Steph., Rhyssa persudsoria Grav., Ichneumon fusorius L. 

 Formicidse: Formica rufa L., Camponotus ligniperdus Mayr. 

 Fossores : Pompilus viaticus Fabr., Ammophila subulosa Latr., Crabro vagus 



Fabr. 

 Vespidse : Vespa crabro L., Vespa rufa L., Vespa vulgaris L. 

 Anthophila: Anthrena ovina Klug., Xylocopa violacea Latr., Megachile 

 ericetorum Lep., Bombus lapidarius Walk., Bombus terrester 

 L., Psithyrus rupestris Lep., Apis melliiica L. 



IV. Anatomical Part 



HIND WING 



The hind wing of Hymenoptera bears on its front margin two 

 kinds of chitinous appendages, the clasping hooks and the marginal 

 bristles, which, during flight, are in contact with the fore wing. Of 

 the hooks two types, differing from each other morphologically, 

 topographically, and in part also functionally, are to be distinguished. 

 These have already been distinguished by Staveley as distal hooks 

 and subbasal hooks. 



The distal hooks, which play the principal role in uniting the wings 

 during flight, are located on the anterior margin of the hind wing, 

 on the upper side of the costal vein. In the Tenthredinidse and Uro- 

 ceridse they are arranged somewhat irregularly, often appearing to 

 form a double row (pi. vii, fig. 3) ; in all the other families, when 

 present in large numbers, a single row (pi. vii, figs. 1, 2, 5, 7-9; pi. 

 viii, figs. 10-13). This hook-row begins, as the figures show, before, 

 at, or behind the place where the cross-vein branches from the costal 

 vein, and extends not quite half way of the distance between this 

 branching and the apex of the wing. This region of the wing is com- 

 monly indicated as the frenum ; therefore, instead of the not very char- 

 acterizing name "distal hooks," perhaps the term "frenal hooks" could 

 be used for these appendages. The hooks of the Tenthredinidas and 

 Uroceridae do not form two strictly parallel rows, but rather a row 

 of hooks standing in groups of twos — in large forms, also in threes. 

 The arrangement of the individual hooks of these groups is irreg- 



