66 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 50 



von Lendenfeld suggested to me in the autuumn of 1902 to investi- 

 gate these structures. I may be permitted here to express my sincere 

 thanks to my highly esteemed chief and teacher, not only in giving 

 me the inspiration for this work, but also for his friendly support 

 during its progress, and to the Smithsonian Institution for a grant 

 from the Hodgkins Fund of that Institution which enabled me to 

 obtain the material and instruments necessary for the work. 



II. Historical Review 



In nearly all entomological text-books and monographs on Hyme- 

 noptera, the wing-clasping apparatus characteristic of this order is 

 mentioned and its function briefly explained ; but in none of these 

 works is there a discussion of the anatomical conditions involved, nor 

 do good figures, particularly of transverse sections, exist of these 

 structures. Chabrier's figures (1822, pi. x, fig. 4; pi. xin, fig. 8) of 

 a transverse section through the fore and hind wing of a bumblebee 

 are so primitive and diagrammatic that it is obvious that the author 

 never saw a transverse section of a hymenopterons wing under the 

 microscope. 1 Other figures of sections through the contact region 

 of hymenopterous wings are unknown to me. The very small num- 

 ber of existing works which treat especially of the clasping hooks of 

 the Hymenoptera are for the most part purely systematic. The best 

 and most detailed of these is Miss Staveley's (i860, Trans. Linn. 

 Soc, London, vol. xxiil, pp. 125-138, pis. 16, 17). She describes 

 the shape and arrangement of the hooks of the hind wing and the 

 groove formed by the hind margin of the fore wing, and gives, based 

 on the morphology of the costal vein and the grouping, topographic 

 position, form and number of the hooks, a key for determining 

 the species which will be discussed in the systematic part of this 

 paper. Staveley mentions (i860, p. 125) that the clasping hooks 

 have already been described and figured by older microscopists with- 

 out giving any exact bibliographical references. Two smaller trea- 

 tises, by Gray (i860, p. 339-342) and Staveley (1862, p. 122-123), 

 are only supplementary to the above-cited work. Recently the varia- 

 bility of the number of hooks in the bee have been studied from the 

 biometric standpoint (Koschewnikoff, cited from Bachmetieff, 1903, 

 P- 41-43)- 



'An instructive diagram of the wing connection (surface view) is given by 

 Sharp (1895, p. 494). 



