TAPEWORM PARASITIC IN THE STICKLEBACK. LOT 
are grouped under this name. The ‘foramina secundaria’ 
described by Kraemer for P. ocellata and P. torulosa, and by . 
Riggenbach for P. fossata, P. abscissa and Corallobothriwm 
lobosum, are muscular pulsatile vesicles which open at the 
posterior lateral margin of each proglottid. Benedict finds no 
such vesicles for P. ambloplitis or for P. ocellata, nor do any of the 
secondary excretory openings seen by me come under the type 
described by Kraemer and Riggenbach.” Throughout their entire 
course, the longitudinal canals give off many side branches which 
anastomose with one another and with the main canal; in many 
cases they end blindly in parenchymatous spaces. At irregular 
intervals, other lateral branches are given off; these gradually 
diminish in width and finally open to the exterior. Im the neck 
this anastomosis is much more evident, at times the main canals 
being lost in the plexus formed. 
At the posterior limit of each proglottis, the four longitudinal 
canals are joined by a circular commissure whose lumen is equal 
to that of the canals. 
The four canals open posteriorly in a notch at the apex of the 
last proglottis. There does not appear to be any such “ Endblase i 
as Kraemer figures, the canals meeting at one point, from which 
a common canal leads to the exterior. Instead of the notch 
there is often a triangular projection at the apex of which is the 
excretory pore. In young forms there is a very pronounced 
“ Endblase” (Pl. IV. fig. 40) into which the excretory canals 
probably open, but this disappears in older specimens. . 
Nervous System. 
Owing to the difficulty of staining it, I have not been able to 
make out the nervous system at all satisfactorily. Anteriovly 
there is a nervous mass, the “brain,” lying between the four 
suckers and just under the fifth; from it are given off two 
longitudinal nerve-trunks which run down the lateral margins 
of the strobilus externally to the excretory system. Benedict 
describes in addition, four transverse trunks arising from the 
anterior nerve-mass, each running straight out between the two 
suckers; about halfway to the margin of the scolex each 
branches into two secondary trunks, which run at right angles 
to their previous course as far as the corresponding sucker. 
Male Organs. 
The testes are spherical bodies, ‘055 mm. dia., about 40 in 
number, scattered throughout the entire space between the 
ovaries and the anterior edge of the proglottis; there is no 
central layer from which they are absent. ach is tightly 
invested with an exceedingly delicate tunica propria, not, as 
Benedict figures, in a loose membrane. In transverse sections 
they appear hollow, with a cavity divided by septa into a number 
of small compartments filled with granular matter. Minute 
vasa efferentia lead from them to a common vas deferens, 
