16 BULLETIN OF THE 



holic specimens of C. socialis the spermatophores from tlie left vas deferens are 

 approximately 0.16 mm. long and 0.035 mm. broad, with a slender neck about 

 a third of the entire length, and a very thin and delicate lamella lor a base. 

 The spermatophores from the right vas deferens are over 2 mm. in total length ; 

 the body itself is oval, approximately 0.40 mm. long and a third as broad ; at 

 one end it terminates in a very long and slender process, two or three times as 

 long as the body ; at the other end there is a similar but slightly stouter 

 process, a little longer than the body, and expanding at its tip into a broad and 

 very delicate lamella, approximately 0.35 mm. long by 0.20 mm. broad. 



Catapagxirus socialis. 

 Jlemipagurus socialis Smith, Proc. National Mus., Washington, III. p. 423, 1881. 



Male. — The part of the carapax in front of the cervical suture is about a 

 fifth broader than long, with the sides nearly parallel ; the front margin sinu- 

 ous, curving slightly forward in the middle and each side between the eye-stalks 

 and the peduncles of the antennae, the middle lobe thus formed being scarcely 

 more prominent than the lateral lobes, each of which is armed with a minute 

 spine, projecting forward just inside of the 'peduncle of the antenna ; between 

 these spines the edge of the front is upturned in a sharp marginal carina, which 

 terminates each side in the spiiTes themselves. The dorsal surface of this part 

 of the carapax is convex in both directions, the protogastric lobes are protuber- 

 ant and well marked, and nearly the whole surface is roughened and more or 

 less tuberculose, with transverse scabrous elevations, which give rise to numer- 

 ous hairs. The branchial regions are slightly swollen, so that the breadth of 

 the carapax posteriorly is greater than in front. All the portions back of the 

 cervical suture are smooth and membranaceous. 



The eye-stalks are about half as long as the carapax in front of the cervical 

 suture, flattened and expanded distaUy, where they are about three fourths 

 as broad as long. The eye itself is black, and the cornea extends round either 

 side so as to be crescent-shaped as seen from above. The ophthalmic scales 

 are less than half as long as the eye-stalks, narrow, triangular, and acute. 



The first and second segments of the peduncle of the antennula are subequal 

 in length, and the ultimate segment nearly once and a half as long as the penul- 

 timate, and almost as long as the eye-stalks. The superior or major flagel- 

 lum is nearly as long as the ultimate segment of the peduncle ; the thick, 

 ciliated basal portion consists of about fourteen segments, and the slender 

 tenninal portion, which is nearly once and a half as long as the basal, of about 

 five very slender and subequal segments. The minor flagellum is about two 

 thirds as long as the major, and composed of about eight segments. The 

 peduncle of the antenna reaches by the eye nearly the length of the last seg- 

 ment, which is about as long as the greatest diameter of the eye. The acicle 

 is slender, acute, and slightly longer than the last segment of the peduncle. 

 The flagellum reaches beyond the tips of the ambulatory legs. 



