PHYLUM ANNELIDA 



227 



A ; slime tubes are formed, and then a band-like cocoon is secreted 

 about the clitellar region. Eggs and spermatozoa are deposited 



FIG. 158. Diagram of the reproductive organs of the earthworm, dorsal 

 view. A, B, C, seminal vesicles; N, nerve-cord; 0, ovary; OD, oviduct; 

 R, egg sac; 5, spermatheca; 5F, seminal funnel; T, testes; VD, vas deferens. 

 (From Marshall and Hurst.) 



in the cocoon, but fertilization does not occur until the cocoon 

 is slipped over the head (Fig. 159, B). 



The eggs of the earthworm are holoblastic, but cleavage is 

 unequal. A hollow blastula is formed and a gastrula is produced 

 by invagination. The mesoderm develops from two of the 



