no.1404. PARASITIC COPEPODS—CALIGIDM— WILSON. 5(37 



the second antennae and the .second maxillipeds. The second antenna? 

 are very much enlarged and three-jointed. The two basal joints are 

 stout and swollen, while the terminal joint is considerably smaller and 

 terminates in a short, stubby claw. The ventral surface of the second 

 joint is parted for a little distance from the distal end by a deep groove, 

 which, starting- at about the center of the distal margin, curves around 

 inward in a broad sweep and disappears quickly upon the ventral sur- 

 face. Along either side of this groove the chitin integument is raised 

 in transverse folds whose anterior edge overlaps the posterior one of 

 the fold next in front, thus giving a rasp-like surface which must be of 

 great assistance in the prevention of slipping. The line of folds along 

 the inside of the groove extends backward, following the sweep of the 

 groove, across the ventral surface to the proximal end of the joint. 

 The folds along the outer side of the groove stop with the groove 

 itself. The terminal joint is exceptionally peculiar. It is about as 

 wide as long and consists essential^ of a very stout claw which is blunt 

 and strongly curved at the tip. But upon the ventral surface of this 

 claw near the posterior margin are two stout accessory spines, each 

 arising from a raised base. And in the center of the basal portion of 

 the claw is a circular, raised area with its surface thrown into longi- 

 tudinal ridges or folds, which project considerably. This, like the 

 rasp-surface on the second joint, must assist in obtaining a firm hold, 

 and are the more needed in the male since these antennae are used for 

 clasping organs. 



The second maxillipeds are much larger than those of the female 

 but otherwise like them, and they evidently serve as accessory clasping 

 organs. 



Total length of female 1mm.; length of carapace 2.1 mm.; width 

 2.1 mm.: length of genital segment 1 mm.; length of the abdomen 

 0.8 mm.; length of egg-strings 3.5 mm. Total length of male 3 mm.; 

 length of carapace 1.75 mm.; width 1.66 mm.; length of genital 

 segment 0.4 mm.; length of abdomen 0.62 mm. 



Color a dark yellow, inclining toward brown in many specimens. 

 {schistonyx, ffx^ 00 to cut or divide, and ' owB, a claw.) 



The National Museum collection includes five lots from the common 

 menhaden {Jh x eooortia tyrannus), numbered 6052, 6060, 6071, 6150, 

 • 51. 57. ( )f these, the first three contain but a single female each, while 

 the last two contain thirteen specimens, two of which are males. They 

 were all obtained from the outside of the body. There is a single 

 female, numbered (5151, from the outside surface of the blue-fish 

 ( Pomatomus saltatrix), and nine lots obtained from the tow. Of these 

 latter, eight are numbered 6038,6070, 6095, 6098, 6099, 6100,6101, 

 811 1. while the ninth is without a number. Thefirstofthe.se lots con- 

 tains four males, the other eight lots are made up of a single specimen 

 each and evenly divided Wet ween the sexes. 



