38 ENTOMOLOGICAL NEWS [Feb., '22 



might be emptied by a crushing in of the erectile lobes on the 

 end of the penis when this organ is inserted into the" female. 

 Because of the hard, heavily chitinized wall of the penis on the 

 side opposite the lobes, any pressure on these would tend to 

 flatten and empty the apical vesicle. The tube connecting the 

 two vesicles suggests that one is efferent and the other afferent. 

 Because the penis of the adult dragonfly contains such flinty 

 chitin, the sections of this organ were made from an individual 

 in the last naiadal instar. By taking the naiad just before 

 emergence, the outer cuticula peels off easily, leaving a soft 

 insect that the razor can slice. While the embryology of the 

 penis was not studied, it is probably true that the vesicles in 

 the tip are imaginations of the body-wall of the penis tip. 

 They are lined with chitin and in this final stage they each con- 

 tain two cuticular exuviae, so that one may legitimately infer 

 that the vesicles exist in the penis during the last three instars 

 of the naiad. The sections figured on Plate III are all of lydia 

 except figs. 28 and 29, which are of incesta. The figures are 

 drawn to show only outlines and cavities. Each, to be under- 

 stood, should be referred by the reader back to its proper level 

 in fig. 17, where, as mentioned above the level of each section 

 is indicated by a letter corresponding to that of the figure of 

 the section. 



Fig. 18 is section A through the bases of the cornua and the lateral 

 lobes. The ridges on the outer sides of the cornua are the distal ends 

 of the medial lobes. 



Fig. 19 is section B through the bases of the cornua and the lateral 

 lobes. 



Fig. 20 is section C and shows the distal meatus and a small slice, 

 ,f:', through the apical end of the distal seminal vesicle. 



Fig. 21 is section D through the distal vesicle, dz', and the distal 

 meatus, dm. 



Fig. 22 is section H through the seminal tube, T, which connects the 

 two vesicles. It shows also a thin slice across the proximal end of the 

 distal vesicle, dv. 



Fig. 23 is section F showing the seminal tube, T, and the tracheae, /;. 

 This figure also shows a cross section of the inflated base, bsc, and a 

 portion of the sulcus of the sternum. It shows also the ventral dia- 

 phragm which is muscular where it attaches to the body wall. This dia- 

 phragm is well developed in the region of abdominal segments 2 and 3 



