390 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



several specimens were found which at first sight had the 

 appearance of maturity, for, in the region of the repro- 

 ductive organs, the body was white, swollen and opaque. 

 When the body wall in this region was punctured, 

 parasites escaped in large numbers. At first they 

 appeared as small, rounded, bodies, white and glistening, 

 each of which proved to be a cyst bounded by a fairly 

 thick wall (PI. VII, fig. 53 a). If a cover-glass be put 

 on, or the cyst be subjected to slight pressure, the wall 

 bursts and its contents are liberated. These consist of an 

 enormous number of extremely minute spores, each one 

 somewhat awl-shaped, and provided with a caudal filament 

 at one end. At the opposite end is a rounded, clear space, 

 and between the two what may be described as the body 

 of the spore, consisting of granular protoplasm and 

 embedded in it an elongated nucleus, apparently broken 

 into two parts (PL VII, fig. 53 b, nu.). This parasite 

 was first described by Kolli, and was named by him 

 Urospora saenuridis. It is a Gregarine of the sub-order 

 Eugregarinae, and tribe Acephalina.* 



Mcintosh (1871) described these parasites as awl- 

 shaped bodies, but he did not appreciate their real 

 significance, as he interpreted them " as stages in the 

 development of the spermatozoa.' ' Nasse also saw 

 them (1882), and interpreted them correctly as 

 parasites occurring in the sperm sac. Minchin* mentions 

 another Gregarine parasite (Synactinomyxon tubificis) 

 as occurring in the sperm sac of Tubifex rivulorum, but 

 I have not been fortunate enough to find it. 



The last parasite noticed as occurring in Tubifex 

 during my observation of the worm was Caryophyllaeus, 

 a Cestode belonging to the family Caryophyllacea of the 



* Vide " A Treatise on Zoology." — Ed. by E. Kay Lankester. Part I, 

 pp. 194 and 298. 



