A Parasitic Copepod. 99 



The sucking proboscis, which is in part made up of the 

 greatly modified mandibles, arises as a styliform organ, mid- 

 way between the second antennae. It surrounds the oral 

 opening. 



The first maxilla are very much reduced in the parasitic 

 Crustacea. In the present form they appear as a pair of 

 minute palp-like organs, situated laterally on the flaring base 

 of the proboscis. 



The second maxilla are well developed, and appear as a 

 pair of long, slender-jointed appendages arising posterior to 

 the second antennae. Their free extremities are seen to be 

 provided with hooks, while a pair of suckers will be found 

 between their points of attachment. 



The maxillipeds are considerably larger, directed poste- 

 riorly rather than laterally, and bear, at their free ends, a 

 peculiar attachment organ. Behind the maxillipeds are four 

 pairs of swimming appendages, of which the first are some- 

 what reduced. Note the median sucker, between the first 

 and second pair of swimming feet. 



The body is terminated below by a flap-like segment that 

 bears a pair of laterally projecting styles. Compare with 

 Cyclops. 



The greatly elongated egg-strings will be found to take 

 their origin laterally from a point midway between the 

 dorsal and ventral terminal flaps. 



Make drawings of the ventral surface and of the several 

 appendages. 



Nauplii, the free-swimming young of many Crustacea, 

 may be secured from the present form and in large num- 

 bers. Tease one of the egg-strings and place its contents 

 under a compound microscope. Each Nauplius will be 

 found to bear three pairs of jointed appendages, which repre- 



