ART. 17. AMERICAN PARASITIC COPEPODS WILSON. 9 



invaginated point between them. The bases of the other pairs do 

 touch and the plates themselves overlap slightly. Posteriorly the 

 third plates slightly overlap the genital segment. Behind these 

 plates on either side is seen another similar lamina, which appears at 

 first sight like one of another pair of plates, but is really the enlarged 

 basal joint of the fourth swimming leg. 



The genital segment is a little longer than wide with rounded 

 cornel's and a wide sinus at the center of the posterior margin on the 

 dorsal surface. On the ventral surface is the base of the abdomen, 

 on either side of which a stout spine extends backward and is visible 

 in dorsal view behind the genital segment and outside of the sixth 

 segment. 



The abdomen is one-jointed and is covered ventrally by a rounded 

 plate, slightly invaginate on its posterior margin and extending 

 considerably beyond the sixth segment lamina in width and length. 

 Near its base this plate bears a pair of modified anal laminae similar 

 to those on Pandams. There are no adhesion pads anywhere on 

 the ventral surface; the exceptionally developed second antennae 

 are abundantly capable of holding the parasite securely in position. 

 Moreover its mode of attachment is entirely different from that of 

 Pandarus. The latter fastens itself to the flat surface of the fins or 

 skin where an adhesion pad can and does function. The present 

 genus fastens to the gill arch and its body hangs free so that adhesion 

 pads would be of no service. The egg strings are attached to the 

 posterior end of the genital segment between the sixth segment 

 lamina and the abdomen and are from one and a half to two times 

 the length of the whole body. 



The first antennae are like those of Pandarus; the second pair are 

 greatly enlarged and are bent into the shape of a sickle. They 

 project in front of the carapace and are visible in dorsal view. The 

 mouth tube is narrow and conical, three times as long as it is wide 

 at the base and sharply pointed. The first maxillae are short and 

 consist of a moderately stout basal joint and a comparatively small 

 terminal claw; they are situated at the base of the mouth tube and 

 point inward toward each other. The second maxillae have a stout 

 basal joint with a projecting knob on its outer margin near the tip, 

 while the terminal claw is bifid for half its length. The basal joint 

 of the maxillipeds is triangular and the stout terminal claw is at- 

 tached to the outer corner of its distal margin. At the inner corner 

 is a cup-shaped hollow into which the tip of the claw fits when it is 

 closed. 



The rami of the first three pairs of swimming legs are two-jointed, 

 those of the fourth pair are one-jointed. The basal joint of the 

 exopod of the first legs is armed with a single spine, while the ter- 



