410 Dr. David Sharp on the structure of the 



16. Edcssa riifo-mnrfiinata, DeGeer (subfam. Pentnto- 

 minoi). Hab. Central America. Figs. 6, 7, PI. XIL, 8, 9, 

 PL XIII. — The rectal-cauda is very large, and is curved 

 from above downwards, so that its orifice is not at all 

 displayed, being, in fact, closely adpressed to the floor of 

 the terminal chamber. The basal part of the cauda is 

 quite cylindrical, smooth, and shining, but the median 

 part of the cauda is thickened, and forms an angular 

 chitinous process on each side ; the two processes, viewed 

 from behind, form together a flattened prominence, each 

 outer edge of which is curved, and is densely fringed 

 with cilife directed outwards ; the lower part of the 

 cauda below the prominence is transversely striate. 



The cedeagus is completely concealed by the cauda, but 

 when this is removed the oedeagus is seen as a hard 

 symmetrically formed polished black object, only the 

 apex of which projects from the theca by which it is 

 closely embraced, the theca forming, in fact, in the case 

 of this species, a part of the oedeagus ; the oedeagus has 

 its free apex deeply and broadly grooved, and at the 

 bottom of the groove in the middle there is a minute 

 round orifice. The lateral appendages are large, and 

 have a very irregularly formed terminal portion. There 

 is no inferior appendage ; but in this species there exists 

 on each side a superior lateral process, projecting from 

 the anterior wall of the terminal chamber : each process 

 is bifid, and the edge of the posterior arm of the lateral 

 appendage moves inward against the cleft. 



17. Eclessa corimta, Burm. Hab. Guatemala, San 

 Geronimo. Fig. 15, PI. XIII. — The general disposition of 

 the parts is similar to what has been described in E. 

 rnfo-marginata, but the shape of the lateral appendages 

 is very different, and the ornamentation of the lower 

 part of the rectal-cauda is very inferior. 



18. Edessa sp. Hab. S. America, Corrientes. Fig. 14, 

 PI. XIII. — Although a very obscure insect, the develop- 

 ment of the rectal-cauda is remarkable, and I have 

 therefore figured it. 



19. Pharypia indchella, Drury. Hab. Pantaleon, 

 Guatemala. Fig. 13, PL XIII. — The segment in tbis 

 species is entirely black, and as the sides are a good deal 

 produced beyond the pieces seated in the chamber, these 



