98 Invertebrate Zoology. 



A PARASITIC COPEPOD 



(Pandarus sinuatus} . 



THE species under consideration leads a parasitic life upon 

 the external surface of the shark. Only females have been 

 collected. Parasitism has wrought many interesting changes. 



External Anatomy. When compared with the free- 

 living Copepod, Cyclops, the present form will be found to 

 have the body depressed, the cephalothorax enlarged, and 

 the posterior portion of the abdomen somewhat reduced. 

 Compare the general outline with that of Cyclops. Is a 

 rostrum present ? Observe the location of the visual organ, 

 and compare with Cyclops. Note the outline of the poste- 

 rior three thoracic segments. The first abdominal segment 

 is greatly enlarged, and within its transparent walls the coiled 

 ovary and oviducts are to be seen. A rounded, flap- shaped 

 piece terminates the body posteriorly. 



Make an enlarged drawing of the dorsal view. 



Examine the ventral surface and note its concavity. The 



first antennce appear as free, blade-like organs along the most 



anterior edge of the cephalothorax. Do they have flexible 



tips ? Are they provided with sensory hairs ? At the base 



of each is a sucking disc. 



Having their origin nearer the median line, and bearing, 

 laterally and posteriorly, a pair of suckers, are the small, 

 hook-shaped second antennce. What is their function? 



