EGGS OF MARINE GENERA 



125 



They are deposited separately in clusters of from 15 to 150, 

 there being about 20 ova in each capsule. It appears that all 

 the species of the same genus have by no means the same method 

 of depositing their eggs, nor do they always produce eggs of at 

 all similar size or shape. Thus, of two British species of iVassa, 



Fig. 39. — Various forms of spawu 

 in Prosohranchiata : A and D, 

 Pyrula ov Busy con ; B, Conus ; 

 C, Voluta musica ; E, Ampul- 

 laria (from specimens in the 

 British Museum) ; all X g. 



N. reticulata lays egg-capsules in shape like flattened pouches 

 with a short stalk, and fastens them in rows to the leaves of 

 Zostera ; M. incrassata^ on the other hand, deposits solitary 

 capsules, which are shaped like rounded oil-flasks. Neptunea 

 antiqua lays its eggs in bunched capsules, like Bucc. undatum 

 (Fig. 40), but the capsules of N. graeilis are solitary. 



In JVatica the eggs are deposited in what looks like a thick 

 piece of sand-paper, curled in a spiral form (Fig. 41). The 

 sand is agglutinated by copious mucus into a sort of sheet, and 

 the eggs are let into this, sometimes (iV! heros^ in regular 

 quincunx form. lanthlna attaches its eggs to the under side of 

 its float (Fig. 42). The Trochidae deposit their eggs on the 

 under side of stones and sea-w^eeds, each ovum being contained 

 in a separate capsule, and all the capsules glued together into 

 an irregular mass of varying size. The female of Galerus 



