706 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



ventral surface and are corrui^ated like a wood rasp. Egg strings as 

 wide as the last joint of the abdomen and nearl}- as long as the entire 

 l)ody, each containing from sixty to seventy eggs. 



Total length, 10 mm. ; length of carapace, 5.35 mm. ; width of same, 

 4.9 mm.; length of genital segment, 3.5 mm.; width of same, 2.(J6 

 mm.; length of abdomen, 1.67 mm.; length of Qg^ strings, 9 mm. 



Color a transparent cartilage gray, exactly like the skin of its shark 

 hosts. 



{gi'acilis, slender, graceful.) 



Male. — The male differs noticeabl}^ from the female in the propor- 

 tion of the bod}' regions. The carapace is orbicular rather than ellip- 

 tical, being actually wider than long, while the remainder of the body 

 is strongly narrowed, thus making the contrast between the two very 

 striking. The free thorax segment lacks the plates upon its dorsal 

 surface, but carries on either side a rounded, swollen protuberance, 

 looking like the stump of a large fourth leg which had been ampu- 

 tated. The real rudiments of the fourth legs are borne on the ventral 

 surface of these protuberances and are short and very slender. 



The genital segment is small and spindle-shaped and has not even a 

 trace of the posterior conical horns found in the female. 



The rudiments of the fifth feet are plainly visible on the ventral 

 surface of this segment. 



The abdomen is narrow and made up of two spindle-shaped segments 

 of about the same size, the anal lamina? are relatively as large as in 

 the female and each terminates in four plumose seta^. 



The second antenna^ are used for clasping organs, and are hence 

 nuich larger and stronger than in the female, and their terminal claws 

 are branched like a stag's horn. There is also a large claw-like spine 

 projecting from the outer margin of the basal joint near its distal end. 



The other appendages are like those of the female, except the second 

 thoracic legs, on the exopods of which, in place of the large claws 

 found in the female, there is a long, conical bod}' protruding from the 

 outer margin of the second joint. 



From the peculiar structure of tnese organs in this and the follow- 

 ing species it seems probable that they are connected in some way 

 with the transference of semen to the receptacles in the genital seg- 

 ments of the female. 



Total length 6 mm. Length of the carapace 3 mm. Width of same 

 3.2 mm. Length of genital segment 1.25 mm. Width of same 0.9 

 mm. Length of abdomen 1.4 mm. 



Color the same as that of the female. 



Nauplius. — Body elliptical, much longer than wide, with evenly 

 rounded ends. Eye spot rather large and of a dark brown color; the 

 other pigment lighter, gathered at the posterior end of the body, and 

 shading anteriorily insensibl}^ into the colorless and transparent region, 



