GLOSSARY 89 



Carapace The shell covering the dorsal and lateral surface,s of 

 head and thorax of a crawfish. 



Caudal Located at the posterior tip of the abdomen. 

 Cephalothora.r A term applied to the anterior part of the body 



of an animal in which head and thorax are not separated 



from one another. 



Chela The large claw of a Crustacean. 



Cleavage The division of cell following the division of the 

 nucleus. 



Cloaca The posterior region of an alimentary canal that holds 

 the waste from the digestive and excretory organs. 



Coelenteric cavity The single cavity of the body of a coelente- 

 rate which at the same time serves as body cavity and di- 

 gestive cavity. 



Conjugation The fusion of two protozoans for an exchange of 

 cytoplasm or of nuclear material. 



Cuticula A thin, non-cellular body covering of many inverte- 

 brates. 



Differentiation The specialization of a group of cells for a defi- 

 nite, restricted function. 



Dorsal "The back;" or more strictly the part of the body di- 

 rected away from the surface upon which the animal nor- 

 mally rests. 



Elytra The horny outer wings of the Coleoptera. 



Fertilisation The fusion of two gametes to form a single cell, 

 the zygote. 



Fission A method of asexual reproduction in which the body of 

 an individual becomes split into two equal parts. 



Gamete A reproductive cell. 



