REVISION OF STREPSIPTERA — PIERCE. 67 



concave ninth segment (hypopygium of Brues), which at its apex is 

 cleft, forming a claw on each side of the base of the oedeagus or 

 genital sheath; the genital sheath is formed by the complete fusion 

 of the paramera into a sinuate tube, reflexed and lying within the 

 concavity of the segment, and with its tip sharply turned upward; 

 near the base of the last curve on the inner angle of the oedeagus is a 

 little pore through .which the very slender penis may be exsertcd. 

 Such a condition is very nicely illustrated on a slide in the author's 

 collection. (See pi. 5, fig. 8; pi. 6, fig. 9.) 



The shape of the oedeagus must be considered of generic and 

 specific value, as it is one of the very few chitinous organs of the body 

 which are not subject to change on drying. In Crawfordia it is 

 slender a,t base, then suddenly inflated, and as suddenly reflexed 

 and narrowed, apically acute. In Stylops crawfordi it is peculiarly 

 notched. In Apractelytra it is a sinuate tube of about equal length 

 almost to the tip, which is obtusely angled. In AcroscMsmus, Pen- 

 toxocera, Trioxocera, Mecynocera, and Elenchus the tube is some- 

 what enlarged basally, suddenly turned', at various angles, apically, 

 and very acute. 



The tenth abdominal segment is large in AcroscMsmus and very 

 small in Pentoxocera and Anthericomma . 



In studying characters of such interest it is always important to 

 find analogies among other insects. In this the writer relied upon the 

 vast storehouse of information possessed by his honored preceptor, 

 E. A. Schwarz. The Psyllida? as shown by Witlaczil and Low (1876, 

 and numerous other papers) have the eighth, ninth, and tenth seg- 

 ments placed in relatively the same manner as in the genus Acroschis- 

 mus, but with the penis lying free between the ninth and tenth and 

 not attached to the ninth to its apex as in Strepsiptera. The " genital 

 zange," or claspers are greatly developed. The penis in Psyllidae is 

 two jointed. It is not known definitely whether this organ is really 

 the penis or only the oedeagus. The genus ( 'orphyra Say, formerly of 

 the Anthicidse, is shown by Horn (1883) to have the exposed oedeagus 

 composed of parti} 7 or entirely separated paramera between which lies 

 the penis. These paramera take various forms. Mr. Schwarz showed 

 the writer how the specialization of the abdominal segments is carried 

 to a remarkable extent in the genus Malthodes of the Telephoridae. 



FEMALE. 



So little is known of the female Strepsiptera that it is very difficult 

 to discuss this general question. It is not because they are scarce, 

 because the females are the most generally met with, but because 

 they lack salient features. In the descriptive matter to follow will 

 be found the main results of the writer's study of this subject, which 



