ZooL— Vol. III.] HEATH— EPIDELLA SQUAMULA. 1 23 



seen to liberate a few yolk-granules, which with irregular 

 halting movements make their way into the larger canals, 

 which are thus continually packed with yolk. The second 

 stage in the egg-laying process is the hberation from the 

 reservoir of a small quantity of yolk, which traverses the 

 vitelHne canal (fig. 13, v. c) and as it passes the opening of 

 the oviduct apparently creates a suction which draws one 

 ^gg from the ovary. These products then make their way 

 to the mould, carrying with them a few sperm and the 

 secretion of the shell glands. The tube behind the mould 

 now constricts, and wave-like movements of the latter ham- 

 mer the yolk and &gg into a tetrahedral mass surround- 

 ed by a shell. The ^gg is now expelled with considerable 

 force from the external opening, and is apparently imbed- 

 ded in the mucous covering of the body of the host. At 

 all events small clumps of ova are thus found in infected 

 fishes. This process is repeated from five to twenty times, 

 when a short period of rest ensues. After specimens have 

 been kept under observation for some time the rate changes 

 and several minutes may be required for the moulding pro- 

 cess. It is a common occurrence in E. sqiianmla that the 

 secretion of the shell glands ceases an hour or two after in- 

 dividuals have been removed from the host, and the yolk 

 and ova are blown hke dust from the mouth of the genital 

 atrium. 



VII. Excretory System. 



In living individuals, especially those which are small 

 and transparent, the flame or terminal cells of the excretory 

 system may be seen distinctly. This is notably the case 

 with those located in the superficial tissues of the pharynx. 

 They possess an irregular stellate form (figs. 15, 16), the 

 processes extending from the cell-body a short distance 

 into the surrounding tissues, and almost invariably the 

 main body of the cell contains from one to eight vacuoles 

 filled with a transparent fluid. In some cases, when the 

 animals have been allowed to remain for some time in a 

 small quantity of water, these may unite into one large 



