REPORT OF THE STATE ENTOMOLOGIST I907 



261 



111 (k) is a sagittal section from the 2d segment of Cordulia with 

 the following structures noted, the letters of which indicate the same 

 structures as in the other figures. ^ is a portion of one side of 



the posterior portion of the framework 

 heretofore described, which is always 

 intimately associated with the posterior 

 hamules. Where the hamules are well 

 chitinized and developed, this part of the 

 frame is correspondingly developed. 

 The hamules appear in some cases to be 

 spread along posteriorly on this frame- 

 work, adding to its thickness. It can be 

 followed easily in all the figures. / is 

 one of the posterior pair of hamules. 

 This hamule in all figures here shown is 

 well developed and in some cases very 

 decidedly hooked at its upper point, g 

 is the anterior portion of the framework 

 which passes beneath the anterior lamina 

 where we find but one pair of hamules, 

 and in this figure, and those following, 

 it passes below and posterior to the first 

 pair of hamules derived from the an- 

 terior lamina. This portion of the 

 framework is the direct support of the penis in Zygoptera and of 

 the sheath in Anisoptera. h is the first pair of hamules developing 

 just before g from the posterior edge of the anterior lamina. The 

 lamina is shown at i covered with hairs on its posterior and ventral 

 surfaces. The first hamule h is not well developed ; however, it is 

 so far formed that one can easily homologize it with those more 

 fully developed in any of the following figures. 



In (/), a sagittal section of Didymops, is shown a farther and 

 decided development of the first hamule marked h in the figure 

 above it. The other structures are similarly placed and easily seen 

 to be homologous. 



In (ill) a very marked development of the first hamule is 

 seen, it being, in this case, almost as large as the second 

 hamule. In (n), Tachopteryx, is to be noted the beginning of 

 the lobed condition' of the first hamule so well shown in (o), 

 Ophiogomphus. In other respects, the parts are similar and 

 similarly placed to those of the preceding figures. In (o) is pre- 

 sented, perhaps the most extreme development in the way of 



Fig. 28 



