154 KANSAS UNIVERSITY SCIENCE BULLETIN. 



curved side being much greater) 0.81 mm., the distal segment 

 0.38 mm., and the club 0.12 mm. 



The subgenital plate has already been mentioned in the quo- 

 tation from Riley. Its measurements are as follows : Depth, 

 0.37 mm. ; length, 0.40 mm. ; greatest width, 0.26 mm. 



Situated at the posterior end of the subgenital plate are the 

 forceps (fig. 10, /", and 35-16). These two pieces are some- 

 what swollen at their bases, seem to be articulated one against 

 the other, and are connected to the subgenital plate by means of 

 a long, thin, tendonous strip, which reaches ventrad to the 

 inner surface of the plate, where it is fastened. The forceps 

 are about 0.29 mm. in length, spread at widest 0.29 mm., and 

 project above the subgenital plate 0.20 mm. 



Female Genitalia. — The genital segment and ovipositor of 

 the female are of great morphological interest. The genital 

 plates have been described by Riley as follows: "Female 

 genital segment a little shorter than the three preceding ven- 

 tral segments together; . . . upper plate a little longer 

 than the lower one, gradually tapering toward the tip, which 

 is straight; . . . lower plate also simple." This is in 

 substance all that I have found in the literature to which I have 

 had access concerning the female genitalia of this family. The 

 genital valves or plates, being of taxonomic value, have gen- 

 erally been included in descriptions of species, but the oviposi- 

 tor remains unmentioned, except in a few cases where it is 

 spoken of as "ending in an acute point" (Edwards). West- 

 wood (1839) mentions it as a "pleurivalve conical ovipositor." 

 I have been unable to find anywhere a treatment of its struc- 

 ture. 



I shall first treat of the two plates mentioned above, and then 

 consider the structure of the ovipositor proper. 



Of these plates, the supra-anal is of the greater interest. It 

 is wedge-shaped, with its apex blunt and its i)roximal end three- 

 sided. It averages in length 0.98 mm. and in width 0.42 mm. 

 Its shape is well shown in 55-4, where the ovate openings 

 at its basal angles can be seen. These latter may be of use in 

 attaching the plate to the abdomen. The plate is somewhat 

 convex but not so much so as the subgenital plate. It bears on 

 its upper surface sensory hairs, probably tactile, and is (luite 

 heavily chitinized except for a large oval space, //, about 0.26 

 mm. long surrounding the anal opening, where the plate is 



