148 MOLLUSCA. 



Female Reproductive System. — The opening of the oviduct 

 has already been noticed. Observe: 



1. The large, swollen portion, the oviducal gland, that lies 

 on the oviduct dorsal to the left branchial heart. 



2. The long convoluted oviduct extending posteriorly from 

 the oviducal gland. It is frequently filled with eggs for the 

 greater part of its length. 



3. The lighter colored, greatly lobulated ovarij, also fre- 

 quently filled with eggs, lying dorsal to the oviduct and visceral 

 sac and extending from the region of the stomach to the end of 

 the body. The ovary is inclosed in a capsule from which the 

 oviduct leads. ' 



4. The nidamental and accessory nidamental glands have 

 been studied and removed. 



5. On the median line of the inner surface of the outer 

 buccal membrane of the female is the sperm receptacle. During 

 the summer this is usually filled with sperm, and is, accordingly, 

 white and conspicuous. Below the receptacle is a modified 

 area for the attachment of sperm reservoirs as they are de- 

 livered from the spermatophores. 



Draw a figure of the female reproductive system. 



Circulatory System. — An injected specimen is desirable. The 

 blood that has been suppHed to the body in general is collected 

 by veins and carried to the branchial hearts. The vessels that 

 collect the blood are: 



1. The pre-cavce. A single vessel carries the blood from the 

 head to the anterior ends of the kidneys. Here the vessel divides 

 into right and left pre-cavse that are intimately connected with 

 the kidneys. The pre-cav£e diverge near the posterior ends of 

 the kidneys and enter the corresponding branchial hearts. 



2. The post-cavce. A pair of very large vessels that return 

 blood from the posterior end of the body. They join the corre- 

 sponding pre-cavse near the anterior borders of the branchial 



hearts. 



3. The mantle-veins. These return blood to the branchial 



hearts from the anterior portion of the mantle. 



