NEW PARASITE FROM THE CRAYFISH. /I 



The excretory pore is terminal. Close in front of it is the excre- 

 tory bladder, which in sections can be seen running dorsally for- 

 ward at least as far as the level of the front of the anterior testis 

 (see Figs. 2, 5). I have not been able to recognize more than the 

 most posterior portion in living animals. According to Looss 

 there is in B. nodulosa a bladder wholly posterior to the hinder 

 testis containing concretions, and from which vessels run forward 

 on either side. I have not seen such concretions in B. cornuta 

 and the bladder is much more extensive than that. 



There are two large testes, 0.3 mm. across, lying one directly 

 in front of the other. In B. nodulosa the testes are smaller, 

 farther apart and oblique. The testes are crowded with active 

 sperm cells, many of them in the last stages of spermatogenesis, 

 and with numerous fully formed spermatozoa. The seminal vesicle 

 and spermatic receptacle are also filled with them. 



Long and slender vasa deferentia run dorsally to the other 

 genital organs, and meet at the posterior end of the large cirrhus 

 sack which is located some distance behind the posterior border of 

 the ventral sucker. The cirrhus sack is very large indeed, much 

 larger than in B. nodulosa. It has a definite outer wall, strongly 

 muscular, enclosing a tubular passage subdivided into two por- 

 tions, a posterior thin-walled part, the seminal vesicle, and an 

 anterior ductus ejaculatorius. This latter is surronded by glan- 

 dular "prostate" cells, is very strongly muscular, having both 

 ' circular and longitudinal fibers. The ductus ejaculatorius is not 

 coiled. I do not know whether it is eversible or not. 



The ovary is generally located on the right side, but not infre- 

 quently it is found on the left (cf. Figs. I and 7). It is always 

 near the ventral sucker, a large and conspicuous organ. There 

 is a short ciliated oviduct, soon joined by first a duct from the 

 seminal receptacle, then one from the yolk receptacle. Certain 

 glandular-looking cells which lie around the oviduct may per- 

 haps represent a shell gland, but a distinct and well-marked 

 organ is not present. Nearly all of my specimens appear to be 

 quite young, and though the uterus contains eggs it is not fully 

 developed. In one, however (Fig. 7), the uterus is longer and 

 evidently more as in fully matured individuals. In this case the 

 uterus is distinctly tubular and winds down and back, passing 



