Prosobranchiata 



535 



BREEDING HABITS 



In Urosalpinx cinerea as in other prosobranchs the sexes are separate, 

 the males being distinguished by a large curved penis which lies at the 

 right side of the head behind the eyes. The two sexes may also be 

 separated by microscopic examination of the gonads, the male glands 

 being whitish in appearance; those of the female yellow to orange in 

 color. The eggs are laid in small, yellow, membranous, vaselike capsules 

 attached to the substratum by a solid expanded foot (Fig. 85). The 

 egg case is flattened vertically with edges marked by keel-like ridges and 

 has, at the top, a small cap through which the fully grown larvae escape. 

 Within the capsule is a soft jelly-like fluid in which the eggs are im- 

 bedded and which serves not only 

 to protect them from mechanical 

 injury but also as a source of food. 

 Spawning begins in the early spring, 

 the first egg cases are found after 

 the water temperature has reached 

 approximately 20 C. for at least 

 one week (Federighi, 1931a; Nel- 

 son, 1931). Spawning continues 

 throughout the summer, and during 

 the fall gradually decreases in 

 intensity. 



The female creeps up to the 



higher levels to spawn. In almost 



all cases if oysters are present in 



the tank the female will climb on 



them to deposit the capsules in 



preference to the sides of the tank. 



While spawning the female does 



Fig. 85.- — Enlarged egg case of Urosal- 

 pinx cinerea showing eggs within. 

 Front and side views are given, a, Cap 

 through which young escape; b, solid 

 expanded foot by which capsule is at- 

 tached to substratum; c, egg. 



_i- 



Fig. 84. — Small, concrete pillar for the 

 trapping of oyster drills. A hook im- 

 bedded at the top facilitates handling 

 when the pillars are to be planted be- 

 low the low water mark. To the hook 

 can be attached a line and buoy, mak- 

 ing the trap easy to find. 



