66 



E. NEWSTEAD — THE PAPATAOI FLIES (PHLEBOTOMUS) 



usually ten transverse and convex ridges, which are so constricted at the margins 

 as to present, in optical section, a distinct and well-marked crenulation. The 

 tubular ducts, which are long and straight, open into the oviduct near to its 

 termination, apparently. 



Sexual Organs of the Male (fig. 12). 



The external characters of the male armature or copulatory apparatus have 

 already been discussed (p. 61) and although the internal sexual organs have been 



-Testis 



Seminal vesicle 



Ejaculafory 

 duct 



Ejaculafory dcigf^ 



Fig. 12. — Male generative organs of Phlehotomus. 



but briefly studied, from preparations examined in optical section, yet a brief 

 account of them may not be without interest. These consist of the following : — 



The testes. These may present a somewhat variable outline, though normally 

 they are elongate-ovate ; they are distinctly paired and widely separated, each 

 possessing its own duct which enters the seminal vesicle at its anterior lateral 

 margin. 



The seminal vesicle consists of a large pyriform sac, the proximal portion of 

 which gradually narrows and merges into the short, tubular, ejaculatory duct. 



The ejaculatory duct is connected with a singular morphological structure 

 which, together with the chitinous rods, presents a slender and somewhat club- 

 shaped though cylindrical process. The outer wall of the swollen portion is 

 formed of thin transparent chitin ; and occupying a central position is a piston- 

 like rod which is dilated at both extremities ; the distal portion somewhat 

 resembles an inverted bulb, the opposite dilatation forming a more or less 

 spherical sac. The space between the central structures is seen to contain 

 delicate muscular fibres ; and the ejaculatory duct leads into the spherical cavity 

 at the lower end of the piston-like rod. Grassi's interpretation of the mechanism 

 of this structure is that it acts like a little pump (pompetta) and regulates the 

 exit of the spermatozoa. Beyond this structure the ejaculatory duct is protected 



