1889.] NEW-YORK MICROSCOPICAL SOCIETY. 15 



The sheaths, especially in species with long ovi])ositors, serve for 

 directing the ovipositor proper. The sheaths are flat, flexible 

 limbs, somewhat expanded near the end, and more or less thickly 

 covered with hairs, which serve as organs of sense of feeling. 

 The ovipositor proper is laterally compressed, and possesses the 

 .elasticity and stiffness of a horse-hair. It is composed of three 

 parts — the middle or dorsal, and two ventral pieces. These are 

 all formed of chitine, and are colored yellow or bronze accord- 

 ing to their thickness. The dorsal piece looks like a ribbon 

 folded lengthwise,' the fold being dorsal, with the edges each 

 forming another plicature inward. The two ventral pieces are 

 also ribbon-like, folded lengthwise, so that, in transverse section, 

 they resemble the letter S. The ledges and grooves thus formed 

 are so joined, that the ventral parts are securely locked to the 

 dorsal part. But the single pieces can freely slide upon each 

 other for a certain distance. 



" The ovipositors of Crypfus and Rhyssa are quite different. 

 In Cryptus the tips are very sharp, like lancets. The ventral 

 pieces, next to the tip, are indented on the outer surface, so that 

 they exhibit very sharp barbs increasing in size up to the ninth 

 barb. The four barbs beyond these decrease in size to mere 

 marks. The pieces are very slender, increasing in diameter up to 

 the thirteenth barb. Here they bear two bristles pointing down- 

 wards towards the tip and inwards towards the ventral piece. 

 From this place up they grow a little thinner. The dorsal piece 

 is nearly without indentation, and increases in size gradually up 

 to the ninth barb of the ventral piece, as seen when all the tips 

 are together. At this place there is a slight recess, and the 

 thickness decreases rapidly about one-third. In this position 

 the greatest diameter of the whole ovipositor proper is between 

 the ninth barb of the ventral pieces and the recess on the dorsal 

 piece ; but, by pulling the ventral pieces backwards, this thickest 

 part can be reduced to the diameter of the remaining ovipositor. 



''''Rhyssa has on the dorsal piece five comparatively small pro- 

 jections. The nine projections on the ventral pieces have no 

 sharp edges, but are rounded off. Through the substance of the 

 single pieces of every ovipositor are seen to pass tracheae and 

 bundles, probably, of muscles. 



" The boring action of the ovipositor can be understood, if we 

 consider that the barbs of the ventral pieces take hold on the 



