NO. 5 INSECT ABDOMEN SNODGRASS 7I 



21, 22. — Two lateral muscles on each side, arising together on an- 

 terior lateral part of median plate of epiproct ; diverging downward 

 to insertions on inner face of upper half of paraproct. 



27,. — ^A very small muscle arising in membrane between epiproct 

 and paraproct ; inserted on extremity of rectum laterally. 



2]^. — Origin anteriorly on inner face of paraproct ; insertion pos- 

 teriorly on circumanal membrane above posterior end of paraproct. 



2^. — Origin dorsally on upper edge of paraproct posterior to 22; 

 insertion ventrally on membrane between lower edges of paraprocts 

 at base of hypoproct. 



BLATTA ORIENTALIS LINNAEUS 



The Blattidae, the Mantidae, and the Termitidae show a most 

 interesting relationship to one another, especially with respect to the 

 female genital apparatus. The termites are very much like the cock- 

 roaches in many of their general features, and particularly in the struc- 

 ture of the ovipositor, though they are placed in a separate order, 

 while, as Walker (1919) says, "in the cockroaches we find many 

 of the peculiarities of the Mantidae in a more pronounced form, as 

 well as special characteristics of their own ". In each of the three 

 families the eighth abdominal sternum of the female is reduced, and 

 the seventh sternum is prolonged backward as a large subgenital plate 

 concealing the eighth sternum and. in the Blattidae, the entire oviposi- 

 tor as well. In the mantids the seventh sternum forms a troughlike 

 structure with mobile, valvular terminal lobes for manipulating the 

 material of the ^gig case ; in the blattids the lobes of the seventh 

 sternum (fig. 24 A, VIISL) enclose a large, distensible vestibular 

 chamber (fig. 23, Vst) in which the ootheca is formed, and in some 

 species retained a varying length of time. Hence, we find in the Man- 

 tidae, as pointed out by Chopard ( 1920) , " almost the same structure 

 as in the blattids of the subfamily Blattinae, though the role of the 

 valves in the two cases may be very different according to the mode of 

 oviposition ". The formation of the egg case in the Mantidae is 

 described by Bugnion (1923). 



The definitive female gonopore in both the Mantidae and the Blat- 

 tidae is located on the reflected dorsal surface of the reduced eighth 

 sternum (fig. 23, Gpr), and therefore has the same position as in other 

 members of the Orthoptera. The statement frequently made that the 

 female gonopore in these families lies between the seventh and eighth 

 sterna is based on an error of anatomical interpretation, as will pres- 

 ently be shown. Above the eighth sternum is the true genital chamber 

 6 



