OF MASSACHUSETTS. 



141 



Prismatic structure, 



Prodissoconch, 



Protandrie, 



Protoplasm, 

 " Seed " scallop, 

 Set, . 

 Spawning, . 

 Spermatozoon, 

 Tentacle, 



Testis, 

 Trochosphere, 



Umbo, 

 Valves, 



Veliger, 



Velum, 



Ventral surface. 

 Ventricle, . 

 Visceral mass, 



Shell made up of prisms. 



Small embryonic shell of a mollusk. 



Having male sexual organs while young, and female 



organs later in life. 

 Cell contents — life substance. 

 A scallop less than one year old. 

 Attaching of scallop by byssus. 

 To set free the eggs or spermatozoa. 

 The male sex cell. 

 A more or less elongated process, usually an organ 



of sense or motion. 

 The male gland which produces the spermatozoa. 

 Stage in embryonic development, in which the em- 

 bryo is spherical and rotates rapidly. 

 The beak or " shoulder " of the bivalve shell. 

 Two valves, the right and left, compose the shell 



of a lamellibranch mollusk. 

 Stage in embryonic development in which velum is 



used as an organ of locomotion. 

 A circular pad covered with cilia and used as an 



organ of locomotion in the early embryonic 



stages. 

 The side opposite the dorsal surface. 

 A chamber of the heart. 

 That part of body containing digestive, generative 



and part of circulatory and nervous systems. 



