no. 1401. PARASITIC COPEPODS—CALIGIDJE— WILSON. 573 



andW. "6; from the pollack {Pollachius virem), 12609, 12625, W. 1, 5, 

 and 8; from the hake {Uropkycis chuss), 12628, 12640, W. 2 and 23; 

 from the hake {Uropkycis tenuis), 6091, 6161, 6165; from the lumpfish 

 {Oyclopterus Iwnpvs), 12617; from the mackerel {Scomber scomorus), 

 12620, 12621, 12622; from the scup {Stenotonius chrysops), 12630, W. 

 20; from the striped bass {Roccus lineatus) , 12613; from the alewife 

 {Clwpea v< rnalis), 12624; from the sturgeon {Acipenser sturio), 12623, 

 W. 21; from Acipenser brevirostrwn, 12610, 12615, 12618, 12629; from 

 the sting ray (Dasyatis centrum), .6188; from the skate {Raia Isevis), 

 6163, L2608, 12633, 12637, 12642, 12643; from Raia ocellata, 6065, 6104, 

 6112; from Raia erinacea, 1399, W. 14 and 24; from the spiny dogfish 

 (Squahis acanthias), 12639; from different sculpins, 8114; from the 

 whiting {Menticirrhus saxatilis), 6164; from the shad {Alosa sapidis- 

 sima), 12612; from the swordfish {Xiphias gladius),W. 12; from the 

 rudder fish {Kyphosus sectatrix), taken in floating gulf weed, W. 11; 

 from the sand shark {Carcharias littoralis),W. 9; from the remora 

 {Remora remora), W. 13; from the crevalle {Caranx m/.ms), W. 15; 

 from the cutlass fish {Trichiurus lepturus), W. 19; from the sand launce 

 (Ammodytes airiericanus), one unnumbered lot. There is also a single 

 specimen of the chalimus stage still attached to a small Monacanthus 

 and numbered W. 20. Other specimens of the chalimus are numbered 

 6110, (!148, 6191, and W. 1. From the surface were obtained lots 

 6097, 6197, 8110, 12614, 12616, 12619, and W. 3, some of which con- 

 tain several specimens. The National Museum also possesses a fine 

 series of specimens from the Durham coast, England, contributed by 

 the Rev. A. M. Norman, numbered 12906. These have been taken as 

 the types of the species, and with them all the American forms have 

 been carefully compared. 



CALIGUS MUTABILIS, new species. 

 Plate VIII, fig. 2 in the text. 



Female. — Carapace about three-sevenths the entire length, as long- 

 as wide, not narrowed anteriorly. Frontal plates well defined, but less 

 than half the width of the carapace; lunules large, circular, and pro- 

 jecting. Posterior sinuses wide and slightly inclined away from the 

 central axis. Median lobe much less than half the entire w T idth and 

 projecting only a little beyond the lateral lobes; the latter blunt and 

 well rounded (fig. '.Mi). 



Thoracic area medium size, the anterior groove almost a perfect 

 semicircle. Free thorax segment short and narrow, about one-fourth 

 the width of the carapace, and contracted into a much narrower neck 

 just in front of the bases of tin 1 fourth legs. Genital segment very 

 variable, according to the age id' the individual as well as the develop- 

 mental stage of the eggs. In young females and in the adults before 



Proc. X. M. vol. xxviii— 04 :;7 



