no. 1653. PACIFIC COAST COPEPODS—WILSON. 445 



rounded and curved slightly inward; the two thoracic areas approxi- 

 mately the same size. Frontal plates well fused with the carapace and 

 less than half the width of the latter, with a shallow central incision. 

 Eyes minute and situated one-third the distance from the anterior 

 margin. The muscles which Ilex the margins of the carapace and 

 which radiate outward from either side of the eves are very promi- 

 nent and show clearly, even in a surface view. The median posterior 

 lobe is the same length as the Lateral lobes and has rather squarish 

 corners, making the posterior margin nearly straight. 



The fourth or free segment is half the length of the genital seg- 

 ment and two-thirds its width, projecting prominently on either side 

 at the bases of the fourth legs. Genital segment ovate, with an 

 evenly rounded outline and prominent posterior corners, showing 

 on the ventral surface a pair of large triangular sixth legs, each 

 armed with three spines. A sixth segment is also partially differ- 

 entiated in front of the base of the abdomen in mature specimens. 

 Abdomen one-jointed, oblong or trapezoidal in form, wider anteriorly 

 than posteriorly and about one-half the length of the genital segment. 



Anal laminae of medium size and curved inward toward each other. 

 Second antennae stout, with a long terminal claw bent at right 

 angles near its tip and armed with a small accessory spine at the 

 center of its anterior margin. 



First maxillae prominent, the circular basal portion three of four 

 times the diameter of the straight terminal part. The second max- 

 illae project far beyond the tip of the mouth tube: each is fully as 

 long as the tube itself and strongly bifurcate, the branches being 

 slender, bluntly pointed, divergent, and as long as the rest of the 

 maxilla. On the basal portion of each is a small papilla, the nidi 

 mentary exopod, bearing a pair of seta'. Mouth tube rather slender 

 and bluntly rounded. Second maxillipeds stout, the basal joint bear- 

 ing a small protuberance on its anterior margin, the terminal claw 

 about the same length as the basal joint and armed with an accessory 

 spine on its ventral surface near the base. 



The basal joint of the first swimming legs is armed with two spine- 

 on its posterior margin, the outer of which is flattened and bluntly 

 rounded, and a single spine on its inner margin. The spine on the 

 basal joint of the exopods of the third leg- is very large and is 

 curved around inward into the form of a sickle. The three terminal 

 joints of the fourth legs are about the same length: the last one bear- 

 two spines, nearly twice as long as the joint itself and toothed along 

 their outer margins, and a third, much smaller spine. 



The coiling of the oviducts is different from that in most species 

 belonging to the genus Lepeophtheirus. The oviducts open just in 

 front of the sixth legs on either side: the external v<^<x strings are 

 slender and about the same length as the body. The cement glands 



