1898-99.] Dr 0. Fuhrmann on Prosthecocotyle torulosa. 649 
The external zone is continuous, which means that it is only in- 
terrupted at the point where the sexual organs pass out. The 
internal zone is confined to the ventral and dorsal surfaces. On 
the internal side of the longitudinal musculature lies a feeble layer 
of transverse muscles, which assists the formation of the com- 
plicated musculature surrounding the terminal part of the sexual 
canals. The dorso-ventral musculature is feeble. 
The nefvous system consists in the strobila of two longitudinal 
nerves which are situated on the outside of the water-vascular 
system. 
The vascular system, which I could only study in the segments, is 
situated rather far from the lateral side (in a proglottides 1*65 mm. 
in diameter the vascular system is 0*4 mm. distant from the side). 
It consists of two ventral vessels and two dorsal vessels placed 
above the first. These two pairs of vessels are surrounded, as in 
P. torulosa , by a musculature. The ventral vessels are joined in 
every segment by a large vessel. 
The male sexual glands are composed of 28 testicles situated on 
the dorsal side of the internal parenchyma. The vas deferens is 
very long, and presents numerous convolutions converging towards 
the left side, that is to say, the side on which issues the sexual 
canals in all the Prosthecocotylce. The interpretations of the male 
sexual apparatus given by Linstow are inexact, which is due 
probably from the fact that this author did not make sections. 
The cirrus-pouch, into which enters the vas deferens, presents a 
form and a structure which is, so to speak, identical in all the 
species of Prosthecocotyle. It is spherical, and contains a vas 
deferens with thick walls. The cirrus, which is very long, passes 
through the canal that I called in the description of P. torulosa , 
‘ male cloacal canal.’ This canal, having the shape of a very 
prominent papilla, has, as well as the genital cloaca, into which 
it enters, a complex structure. The papilla and cloaca are carpeted 
by the continuation of the cuticula of the body. Their muscular 
system is composed of internal circular fibres and of others with a 
radial disposition. The whole is surrounded by a system of fibres 
proceeding from the transverse musculature of the parenchyma. 
So the whole presents, in transverse sections, the structure of a 
sucker (figs. 6, 7). Into the deep genital cloaca, with wrinkled 
YOL. XXII. 2/12/99 2 T 
