SEA-FISHERIES LABORATORY. | 97 
the inner and outer walls of the bulbus. There are no 
other fibres in the latter than these, and it is somewhat 
difficult to determine what part they play in the emission 
of the semen, which is presumably the function of the 
ejaculatory bulb. Possibly they only act in dilating the 
latter, so that it becomes filled with spermatozoa from the 
vas deferens. The coniraction of the wall of the cirrus sac 
will then cause an increase of pressure of the contained 






Felracior of 




ihe Cirrus __. fe 
Vas deferens ----- 
Cirrus a" 
Cirrus Sheath\ | - fog 
Ducts. y _-f Urerus 
ejacu/alorius jy y, |” Bulbus 
BA 'eyaculalorius 
Sl 
OO eae 
— Common genital aperture 
SJ. 
Fie. 3. Diagrammatic longitudinal section of the cirrus sac. 
tluid, and this will be exerted on the outer wall of the 
bulbus, thus causing an emission of the semen from it, at 
the same time as the penis 1s extruded. 
The lumen of the ejaculatory bulb is continued as 
that of the ductus ejaculatorius. The latter is a narrow 
3 
tube with firm, hard, “‘ chitinous’’ walls. Leaving the 
ventral end of the bulbus it turns dorsally, being 
surrounded with fibrous connective tissue running mostly 
