68 PROCEEDINGS OF THE NATIONAL, MUSEUM. vol. fio 



tainecl from the same localitj' and host July 9, 1904, and have been 

 given Cat. No. 54072, U.S.N.M. 



External specific characters of female. — Body elongate, largest 

 at the anterior end and regularly tapered to a blunt point at the pos- 

 terior end. There are four free thorax segments, diminishing regu- 

 larly in width but of very different lengths, the fifth segment being 

 much the longest and the second (first free) segment the shortest. 

 The first segment, being fused with the head, is always partially and 

 sometimes completely hidden beneath the posterior margin of the 

 carapace. Occasionally it is quite distinctly separated from the head, 

 but this is due to lack of maturity, the tendency being for it to appear 

 plainly in undeveloped females, and then gradually disappear as 

 development progresses. 



Carapace nearly as long as the second and third segments together, 

 subquadrilateral in outline with rounded corners and a deeply emargi- 

 nate posterior border. The lateral margins are also often more or 

 less emarginate. The first antennae are prominent on the anterior 

 margin, and their basal joints have an appearance similar to the 

 frontal plates in the Caligidae. The dorsal surface of the carapace 

 is grooved similarly to the cephalic area in the Caligidae, but no 

 eyes can be detected. Both the second maxillae and the maxillipeds 

 project beyond the margins of the carapace and stand out promi- 

 nently in dorsal view. 



There are four pairs of biramose swimming legs, together with a 

 fifth and sixth pair, which are rudimentary and consist merely of a 

 lamellar joint without rami. The sixth pair can be seen only on 

 immature females and apparently disappear in the mature adult. 



The ^^'g sacks are attached to the sides of the genital segment near 

 its posterior end. Each is fully as wide as the genital segment itself, 

 considerably more than half as long as the entire body, and contains 

 from 8 to 12 large eggs. 



The abdomen is small, no longer and much narrower than the geni- 

 tal segment, and two-jointed. The basal joint is a little the wider 

 while the terminal joint is much the longer, and is tipped with two 

 tiny anal laminae, whose setae are hardly visible. 



The first antennae are long and slender, and are made up of two 

 large and stout basal joints and six short terminal ones. 



The basal joints are fully half the entire length of the antenna, and 

 on the dorsal surface the second of these joints ends in two stout 

 claws which curve over ventrally on the posterior side of the third 

 joint. On the ventral surface both basal joints are armed with a 

 row of stout spines along their anterior border, while near the distal 

 end of the second joint is a circular disk carrying two strong spines. 

 From beneath this disk a large spine extends laterally, parallel with 



