42 



course alono- each side of the median line to the external 

 openings. Each cement gland (Plate V., figs. 4, 5 and 7, 

 sg.) is a long crystalline organ of nearh' the same length 

 and breadth as the oviduct, lying ventrally to it. The 

 anterior part terminates at the base of the neck, in a blunt 

 end. The posterior end communicates with the oviduct 

 just inside the opening to the exterior. 



The structure of the ovary of Lerncea differs con- 

 siderably from that of Lepeo'phtheiriis. In the cyclops 

 stage it consists of a mass of minute nucleated cells. In 

 the adult condition there are no tubules, and all the eggs 

 are in close contact. The size of the eggs in the ovary 

 of the adult varies from '04 to "08 mm. They are of the 

 same structure and undergo the same changes in their 

 passage along the oviduct as the egg^ of LepeophtheiruH 

 when they enter the thoracic ends of the oviducts. The 

 ovisacs consist of long slender tubes very much twisted. 

 (Plate IV., fig. 1, OS.). When straightened out each tube is 

 often found to attain the length of seven or eight inches. 

 The eggs are arraneed in a single column, and tlie period 

 of incubation is of the same duration as in Lepeophtheirus. 

 The death of the parent or detachment of the ovisacs has 

 no effect on the vitality of the embryos. 



Fertilisation of the female is effected during the fixed 

 period of the cyclops stage. The spermatophores are 

 attached to the female in a similar manner to that 

 described foi' Lepeophtheirus. The contents pass into the 

 receptacula seminis, and the empty sacs fall away. They 

 are then replaced by others in succession, until the recep- 

 tacula are filled. Each fully charged receptacuhira repre- 

 sents the contents of four spermatophores {rep., Plate 

 IV., fig. 4). At first there is a distinct division between 

 each lot, but this soon disappears, and the whole becomes 

 one mass of spermatozoa. From a large number of 



