A NEW SPECIES OF PARASITIC COPEPOD, WITH NOTES 

 ON SPECIES ALREADY DESCRIBED. 



By Charles Branch Wilson, 

 Department of Biology, State Normal School, Westfield, Massachusetts. 



Three males and two females of an undescribed species of parasitic 

 copepod were obtained by Dr. William A. Hilton from a " swordfish " 

 at Catalina Island, off the coast of Southern California, in 1917, 

 which are herewith described. 



GLOIOPOTES COSTATUS, new species. 



Plate 21. 



Host and Record of S'pecimens. — One male and female are still 

 fastened together and are made the cotypes of the new species (Cat. 

 No. 51040, U. S. N. M.) ; the others are free and become paratypes 

 (Cat. No. 51041, U.S.N.M.). 



Specific characters of female. — Carapace elliptical, as wide as long, 

 squarely truncated posteriorly and not very strongly arched ; frontal 

 plates indistinct; posterior sinuses wide but shallow, the tips of the 

 lateral lobes curved inward until they touch the sides of the third 

 segment. The carapace is reinforced by very stout ribs; the posterior 

 ones in the lateral area on either side sweep around backward into 

 the lateral lobes, and are double at their base for some distance. The 

 thoracic area is marked off in much the same pattern as in Gloiopotes 

 ornatus., with the triangular eye area inserted in the center of its 

 anterior margin. The fourth segment is about the same length and 

 width and is covered with a pair of kidney-shaped dorsal plates, 

 which are inclined at an angle to the body axis, with their concave 

 sides outward. They reach quite a distance backward over the ante- 

 rior end of the genital segment, leaving a wide median posterior 

 sinus between them. 



The genital segment is horseshoe-shaped, as in other species of the 

 genus; it is contracted into a neck anteriority, then widened abruptly 

 to half the width of the carapace and prolonged backward in a stout 

 lobe on either side of the abdomen. The sides of the segment are 

 convex with a smooth curve, lacking the shoulders at the anterior 

 corners, which are found in oriiatus. The tips of the lobes also curve 

 inward so far that they almost meet on the midline ; the dorsal sur- 

 face and the lateral margins are smooth. Instead of the flap or 



Proceedings U. S. National Museum, Vol. 55— No. 2274. 



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