REPORT OF THE STATE ENTOMOLOGIST I907 255 



specialized Libcllulinae there are scarcely any indications of 

 these parts in the nymph externally visible, but they are easily 

 recognized in most Corduline nymphs. 



In (s) two structures are noted meeting in a median line and 

 apparently a part of the lamina anterior to them. These 

 structures are the evidences of the strongly developed first pair 

 of hamules which come from the posterior portion of the an- 

 terior lamina. Comparisons of this figure with the imago will 

 bear out this conclusion. 



Comparative anatomy of adult forms 

 Let us now proceed to a more careful examination of these 

 parts and their relations in the several major groups of Odonata, 

 beginning with a generalized representative of the Libellulinae. 



Figure 21 represents the conditions found in Peri- v_ y 



tbemis. The anterior lamina here (figure 21 ) / ; is sim- 1/k^"^ L- 



pie in structure and has already been described, special M}f\f\ 

 attention being called to the notches at the sides, and to ^^-^^^==3^^^ 

 the lateral divisions marked k, for these indicate the Fig. 21 



source of the anterior pair of hamules. The haniule // is attached 

 anteriorly to the portion of the framework which passes forward 

 under the anterior lamina, as well as to v which here is only a 

 line of chitin passing posteriorly to the sheath j. This line of 

 chitin is to be found in all other forms in both suborders and it 

 seems to be a part conjoining the rear ends of the second pair of 

 hamules. Wherever the hamules are well developed, this line of 

 chitin is well developed, as will be shown farther on. .? is the 

 sheath of the penis which is transparent and poorly chitinized, 

 another characteristic of this family. This sheath is attached at 

 two points to the line v connecting the hamules, as well as to the 

 anterior portion of the U-bar where it begins to curve upwards. 



In Nannothemis, Perithemis and Celithemis these condi- 

 tions were found to be approximately the same. In the last was 

 found the least chitinized condition of the portion of the frame- 

 work marked v connecting hamules or either side of the 

 sheath. In all other forms examined it was well developed and 

 in some it was very thick and strong. As far as complexity or 

 specialization of parts is concerned, the author concludes that 



