444, W. A. HASWELL. 
perfectly understood ; and various conflicting statements have 
been put forward as to their structure and functions. 
The account of them given by von Graff (15), in the case of 
A. cinereus, is assuredly incorrect, unless that species differs 
in a very thorough and radical manner from the Australian 
form. He represents the female genital aperture as leading 
into a sort of vestibule, from which, in turn, lead three 
passages—a median and two lateral. The former is a short 
and wide passage leading backwards into a cavity—the cavity 
of the bursa seminalis,—which becomes filled with a mass of 
spermatozoa as the result of an act of copulation. ‘I'he two 
lateral passages are much narrower than the median; they 
curve outwards and backwards and open into the bursa 
seminalis. In the posterior part of each of them is lodged 
the corresponding chitinous end-piece, the base of which is 
supported on the mass of spermatozoa, while the apex is 
directed towards the external opening. Hach mouth-piece 
is described as a curved, tapering rod, made up of a series of 
perforated chitinous discs, the central canal being bounded 
by a longitudinally striated membrana intima. Surround- 
ing the chitinous tube is a layer of ring-shaped cells, each of 
which is the matrix cell, or formative cell, of one of the 
chitinous discs. 
Von Graff regards the mouth-pieces as organs capable of 
eversion, and of acting as organs, by means of which sper- 
matozoa are transferred to another individual, the lateral 
passages, with their chitinous mouth-pieces, being regarded 
by him as the parts by means of which the ova are fertilised 
when discharged. Butin Amphicherus and Polycherus, 
as in Convoluta, it has been shown by Pereslawzewa (21), 
Repiachoff (23), Mark (20), Gardiner (10), and others, that 
the eggs are internally fertilised. 
A deeper insight into the structure and mode of action of 
these organs was attained by Mark (20), who studied them in 
his Polycherus caudatus, in which there are a number of 
mouth-pieces on each side, instead of merely one as is usually 
the case in A. cinereus. “ Hach chitinous structure consists 
