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BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



with a stout median spine near the posterior margin. The rest of 

 the body, except the last two segments, with a row of smaller denticu- 

 late spines along each side of the dorsal midline, one spine on the 

 posterior margin of each segment, including the median division of 

 the genital segment. Rostrum tongue-shaped, constricted at its base, 

 with an angular ledge at the center of each lateral margin, bearing 

 a filiform seta. Penultimate abdominal segment with a row of four 

 spines on its posterior margin, each tripartite at its tip. Caudal 

 rami stout, three times as long as wide, apical setae about half the 

 body length. First legs narrow and elongate, especially the basipod 

 segments; exopod 2-segmented, scarcely more than one-third the 

 length of the basal endopod segment. First antennae 6-segmented, 



the four basal segments five times as long 

 as the two terminal segments ; exopod of 

 second antenna attached to the side of 

 the basal endopod segment, 1-segmented, 

 with four setae. Distal segment of fifth 

 legs strongly constricted at its base, 3- 

 lobed at its tip, each lobe with one seta, 

 the inner one the longest. Basal expan- 

 sion reaching beyond the tip of the distal 

 segment, much narrowed at its tip, with 

 one apical seta and three widely separated 

 ones on its inner margin. Total length, 

 1.25-1.35 mm. 



Male. — About the same length as the 

 female, but more slender. First antennae 

 enlarged, the fourth segment swollen pos- 

 teriorly and with two or three anterior 

 toothlike processes, the terminal segment 

 ending in a sharp point. Exopod of 

 third legs very wide and stout, its end segment twice the length 

 of the second segment, with seven coarse spines, three apical, two 

 outer, and two inner. Third endopod 3-segmented, the spine at the 

 distal corner of the middle segment reaching the tip of the end seg- 

 ment. Distal segment of fifth legs very small, 3-lobed at its tip, 

 each lobe with a seta; outer process of basal segment longer than 

 distal segment, inner expansion obsolete, without setae; rudiments 

 of sixth legs present. Total length, 1.25-1.35 mm. 



Remarks. — This is one of the largest species of the genus and can be 

 recognized at once by the longitudinal rows of dorsal spines and by 

 the very large and peculiarly shaped rostrum. This is the first 

 record of its occurrence on American shores. 



Figure 173. — Laophonte hor- 

 rida: a. Female, dorsal ; 6, 

 female, fifth leg ; c, male, 

 fifth and sixth legs 



