NO. 1404. PARASITIC COPEPODS—CALIGIDyE— WILSON. 567 



the .second iiiiteniiie and the .second inaxillipeds. The second antennte 

 are veiy much enlarged and three-jointed. The two l)asal joints are 

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

 terminates in a short, stul)bY claw. The ventral surface of the second 

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

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

 inward in a broad sweep antl di.sappears (juickly upon the ventral sur- 

 face. Along either side of tliis 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 l)ackward, 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 al»out as 

 wide as long and consists essentially of a very .stout claw which is blunt 

 and strongly cui'ved at the tip. But upon the ventral surface of this 

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

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

 the claw is a circular, rai.sed area with its surface thrown into longi- 

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

 nisp-surface on the second joint, nuist assist in obtaining a firm hold, 

 and are tlie nu)re needed in the male since these antenna' are used for 

 clasping organs. 



The second maxillipeds are much larger than those of the female 

 l»ut otherwise like them, and they exidently .serve as accessory clasping 

 organs. 



Total length of female 4 mm.; 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 o..5 nun. Total length of male 3 mm.; 

 length of carapace 1.75 mm.; width 1.60 mm.; length of genital 

 segment O.-l mm.; length of abdomen 0.02 mm. 



Color a dark yellow, inclining toward )»rown in many specimens. 

 [ftchistonyx, (Tj/CcJ to cut or divide, and ' ovvB a claw.) 



The National Museum collection includes five lots from the comiuon 

 menhaden {Bnroortia tyrannus), numbered 6052, 6060, 0071, 6150, 

 6157. Of these, the tir.st 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 bod3\ There is a single 

 female, numbered 6151, from the outside surface of the blue-tish 

 {PoniatoiiiUK xaJtatr!,!')^ and nine lots obtained from the tow. Of these 

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

 8111, wdiile the ninth is without a number. The first of these lots con- 

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

 each and evenly divided between the sexes. 



