54 SYNOPTIC KEY 



Ctenidia: Gills. 



Cuticula: A definite covering over the outside of a cell or body. 



Dental formula: A device for showing the number of incisor, 

 canine, premolar, and molar teeth on one side of each jaw. 

 The numbers above the line represent the teeth of the upper 

 jaw. 



Dorsal: Pertaining to the back, usually the upper surface of an 

 animal. 



Dorsoventrally: Pertaining to the relation between the back and 

 belly. An animal flattened dorsoventrally has its dorso- 

 ventral axis shortened and extends laterally as a ribbon. 



Ectoparasit^c: Parasites attached to the outside of the animal 

 which serves as their host. 



Ectoplasm: The outer layer of protoplasm in a cell in which the 

 outer and inner parts of the cell differ markedly in structure 

 {See Endoplasm.) 



Elytra: The thickened wing covers of beetles. 



Endoparasitic: Parasites Hving on the inside of the animal which 

 serves as their host. 



Endoplasm: The inner part of the protoplasm of a cell in which the 

 outer and inner portions differ markedly in structure. The 

 endoplasm surrounds the nucleus. See Ectoplasm. 



Exumbrella: The outer, convex, aboral surface of a medusa as 

 opposed to the subumbrella which is the concave surface 

 around the manubrium. 



Filiform: Slender cylindrical form pointed at both ends. 



Plagella: Long whiplike projections from cells, capable of move- 

 ment. 



Free living: Animals which are not parasitic. 



