42 Annals Entomological Society of America [Vol. XV, 



hypandrium, much like that of many Tettigonoidea, and 

 usually bears styli upon its hind margin. It is a coxosternum, 

 sternite and coxites being completely fused. It is often very 

 asymmetrical, sometimes bearing a lobe or process on one side 

 but not on the other, and the styli are often unequally devel- 

 oped and asymetrically placed. The paraprocts are broad and 

 depressed and are usually chitinized beneath, at least in part; 

 the chitinized portions meeting the margin of the tenth tergum 

 and thus appearing to represent the tenth sternum, with which 

 they have been identified by Chopard ('17).* They are fre- 

 quently strongly asymm.etrical and may bear a hook on one 

 or both sides. The upper surface and sometimes a pair of mesial 

 lobes are membranous. 



The genitalia are strongly asymmetrical and show a wide 

 range of variation. They consist, essentially, of an sedeagus or 

 penis, upon which the ejaculatory duct opens, sometimes at 

 the base, sometimes upon a retractile spine (virga) ; and two 

 outgrowths or processes, primitively dorso-lateral to the penis, 

 each of which bears one or more chitinous parts. These are 

 usually very differently developed on the right and left sides, 

 and their relative positions seem to be primarily similar to that 

 of the two lobes in Grylloblatta, i. e., Ihey are obliquely shifted, 

 so that the right process overlaps the left. In what appears 

 to be the most primitive form met with in the types studied 

 (dextral process of Blattella), their structure consists of a freely 

 projecting shaft, whose base has been deeply sunk into the 

 haemocoele, to serve as an apophysis for the attachment of 

 protractor and retractor muscles, while from the folds sur- 

 rounding the pocket thus form.ed secondary chitinizations for 

 the attachment of muscles may also develop. Such a form of 

 process is protrusible and retractile to a certain extent, but 

 apparently cannot be complete^ ensheathed. In the left 

 process of Blattella, however, we have a modification of this 

 form, in which the shaft has the form of a hook and can be 

 completely withdrawn into a deep membranous pocket or sheath 

 whose walls are without secondary chitinizations, and which is 

 not prolonged into an apophysis, the muscles being attached 

 directly to its base, 



* See p. 7. 



