262 BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



in number. In the fourth legs each ramus is terminated by a broad 

 lanceolate lamina, with a single seta outside of it and a spine at the 

 outer corner. The exopod segments of all four pairs of legs are 

 fringed with spinules on their outer margins in addition to the 

 regular spines. The fifth legs are 2-segmented, narrow and elon- 

 gate; the basal expansion reaches beyond the center of the distal 

 segment and is armed with two apical setae and one on the inner 

 margin. The distal segment is twice as long as wide, contracted 

 at its base and rounded at its tip, with five marginal setae. Total 

 length, 0.45-0.55 mm. 



Male. — A little smaller and more slender than the female; the 

 urosome relatively narrower, the genital segment not divided. The 

 anal segment is fully as long and as wide as the penultimate seg- 

 ment, and the lateral stylets on the caudal rami are even larger than 

 in the female. The first antennae are twice geniculate and 9-seg- 

 mented, the segments but little swollen, the fifth segment a little 

 longer than the second, each of them with two setae close together 

 on its posterior margin. The fourth segment is very short, with a 

 single anterior seta; the end segment has a longitudinal row of setae 

 along its dorsal surface. In the second antennae the basal endopod 

 segment is three times as long as the distal; the exopod is longer 

 than in the female but still 1-segmented and tipped with two setae; 

 the distal segment has three apical setae which are considerably en- 

 larged basally and only slightly geniculate. The terminal claw of 

 the maxilliped is slender, is not jointed near the base as in the 

 female, and carries only two inner spinules. The first four pairs of 

 legs correspond Avith those of the female and do not show any sex- 

 ual modifications. The fifth legs are reduced in size; the basal ex- 

 pansion is much narrower and does not reach the midline, but it 

 carries similarly two apical setae and one on the inner margin near 

 the tip. The distal segment is also twice as long as wide, projects 

 less than half its length beyond the basal expansion, and has four 

 apical setae, the second outer one filiform. Total length, 0.4—0.5 mm. 



Remarks. — This species can be recognized at once by the large 

 stylets on the caudal rami, standing out at right angles to the long 

 axis of the ramus, and by the lanceolate laminae at the tips of the 

 rami of the fourth legs. Each ovisac contains but two eggs, the 

 diameter of which is at least three-fourths of that of the genital 

 segment itself. It is a rapid swimmer and also moves about among 

 the sand grains with great agility. 



Family LAOPHONTIDAE 



Genus LAOPHONTE Philippi, 1840 



Body slender, the metasome passing insensibly into the urosome, 

 the segments with conspicuous constrictions between them; head 



