278 THE CANADIAN ENTOMOLOGIST 



THE DORSAL PYGIDIAL GLANDS OF THE FEMALE 

 COCKROACH, BLATTELLA GERMANICA.* 



BY E. H. DUSHAM, ITHACA, N.Y. 



While engaged in the study of the body wall of the cockroach, 

 the writer's attention was attracted by peculiar and previously 

 unnoted structures on the dorsal side of the 10th abdominal seg- 

 ment of the female. These are represented in Fig. L D. They 

 consist of three groups of depressions in the cuticula at the very 

 anterior portion of the segment, one large group at the centre, 

 and a smaller group on each side of this. These depressions are 

 of various sizes, the larger ones, however, being found in the 

 middle group. 



In fresh material, these structures are not visible from the 

 dorsal side, being covered by the posterior part of the 9th segment. 

 However, by stretching the intersegmental membrane between 

 these two segments, the depressions are readily observed, especially 

 in material which has been boiled in potash and stained with 

 Eosin or Gentian Violet. 



Under the oil immersion lens it will be seen that the smallest 

 depressions are single, and contain a single pore at the centre 

 (Fig. 2). The larger depressions on the other hand include numer- 

 ous smaller depressions, the number ranging from two to twenty, 

 according to the size of the depression. Each of these smaller 

 depressions likewise has at its centre a single pore. Viewed from 

 the surface it will be seen (Fig. 2) that the smaller depressions 

 with their pores at the centre, appear as well defined areas, simulat- 

 ing somewhat the areas which characterize the surface of the 

 cuticula in other regions of the body. In cross-section (Fig. 3) 

 it will be seen that what appear as lines dividing the different 

 areas when viewed from the dorsal surface, are in reality smaller 

 ridges. It will also be noted that the pores extend through both' 

 layers of the cuticula. 



The presence of pores in the cuticula indicated that glandular 

 structures were present in that region. Accordingly cross and 

 longitudinal sections were made through these parts, varying in 



*Contribution from the Entomological Laboratory of Cornell University. 

 August, 1918 



