66 R. NEWSTEAD—THE PAPATACI 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 
Ejyaculatory duct 
Eyaculatory 
ducts 
Penis 
AD 
Eyaculator 
duct A 
MY (CH 
b QL’, jaculatory ducts 
a) 
Fig. 12.—Male generative organs of Phlebotomus. 
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 duet is protected 
