SEA- FISHERIES LABORATORY. 129 



The sections of the uterus can be recognised by the presence 

 of the eggs. The apparently empty spaces in the section, 

 or those which contain fine granular matter are sections of 

 the branches of the alimentary canal and of the large excretory 

 canals. 



Only one of the cysts examined — one which was situated 

 on the external surface of an outer gill-bar, contained separate 

 worms. About half a dozen of these were dissected out by 

 Mr. Scott, and the worms were fixed and stained. They varied 

 in length from about 1J to 2 cms., and in diameter from J to 

 rather more than 1 mm. The worm had a distinct neck, and 

 the hinder part of the body was thicker than the neck, but 

 there was no large expansion of the posterior body, like that 

 present in some other species belonging to the group. The 

 worms coil up spirally and cannot easily be straightened out 

 during fixation. One was straightened out during the process of 

 dehydration, and even cut into serial sections, but the process 

 of straightening led to the collapse of the branches of the 

 alimentary canal, and the excretory canals, so that it was 

 difficult to trace the genital ducts in these sections. Another 

 worm was cut longitudinally as the coiling after death took 

 place in one plane. PL I, which represents the arrangement 

 of the genital organs, is based almost entirely on this 

 preparation. The most conspicuous organ is, of course, the 

 female genital duct. This starts from the shell-gland as a 

 short thin oviduct and then runs forward as a narrow duct ; 

 it is the first segment of the uterus, and contains small, 

 round, thick-shelled eggs. Near the anterior end of the body 

 it turns back and runs posteriorly as the second part of the 

 uterus, and then reaching the posterior end of the body it 

 runs forward again as the third segment of the uterus. It 

 dilates greatly in some of the worms near the anterior end. 

 Then there is a short, thick-walled, very narrow, efferent 

 genital duct which opens at the tip of the genital papilla. 



