566 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxviii. 



the second joint, at the anterior corner. Tlie terniintil claws on these 

 legs are, peculiar in that they are all thrcM' l)ir-aniose, the division 

 extending well l)eyond the middle of the claw. Of the two l)ranches 

 the endopod is nearly straight, while the exopod is strongly curved. 

 Furthermore, the appendage at the inner corner, between the termi- 

 nal claws and the posterior plumose seta% instead of heing a smaller 

 plumose seta, as is usually the case, is here a long and stout claw, 

 unbranched and curved over strongly ventrally (Hg. 75), 



This peculiarity of the terminal claws has given the species its 

 name. Tlie other legs are like those ordinaril}' found on Caligus. 

 The spines upon the last two joints of the exopod of the second legs 

 are very small and insigniricant, while that upon the basal joint of the 

 exopod of the third legs is large and stout. The rami of these third 

 legs are widely separated and th(^ endopod has but a single joint. 



The fourth legs are very slender and weak, three-jointed, with the 

 basal joint as long as the other two. The second joint has a spine at 

 its distal end and another small one on its outer margin. The ter- 

 minal joint has the usual three terminal spines, of which the inner 

 one is fully twice as long as the second, and a siuall spine on its outer 

 margin. 



The fifth legs are so far reduced as to be invisible except by ver}- 

 careful scrutiny upon the ventral surface. 



Male. — The sides of the carapace are not arched as in the female 

 but are nearly straight lines, and the anterior conti'action is nuich 

 inore decided. The posterior sinuses are a very broad U -shape, 

 throwing the tips of the lateral lobes outward away from the median 

 lobe. This, together with the sharp angles of the ti'ansparent Ix^'der, 

 gives the carapace a marked trapezoidal form, the anterior and pos- 

 terior sides parallel, the former onl}- two-fifths the length of the 

 latter, while the right and left sides are equally inclined. The trape- 

 zoid formed upon the dorsal surface by the grooves between the dif- 

 ferent areas is the exact reverse of this formed by the margin, and is 

 not as clearly defined as in the female. The thoracic area is more 

 nearly semicircular in outline than quadrilateral (fig. 65). 



The large basal joints of the third legs project from either side of 

 the median carapace lobe and do not overlap the lateral lobes, nor 

 even reach them. The genital segment is very small, scy,rcely wider 

 than the abdomen, as wide as long, with evenly rounded sides. The 

 fifth legs appear as very small ])apilhe upon the lateral margins near 

 the posterior end of the segment. The abdomen is two-jointed, the 

 joints of the same diameter but the terminal one four times the length 

 of the basal. 



Anal papilla' very large and foliaceous, with long and slender i)lumose 

 seta\ 



The only ap])endages which are at all worthy of special mention are 



