9922 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
figured by Giesbrecht in his Naples monograph and the male recorded 
as unknown. Since that time the description and figures of the fe- 
male have not been improved and only two statements with regard to 
the male have appeared. Esterly (1905, p. 156) said “head as in the 
female,” and that constituted his entire description. A. Scott recorded 
two young males in the Siboga plankton but gave no word of descrip- 
tion. The pencil drawings of this species made by Sars included both 
sexes and were so good that they are here reproduced and a complete 
description is given. 
Female.—Metasome stout and more or less cylindrical; head nar- 
rowed anteriorly with a median crest, which is raised into an antero- 
dorsal cap or helmet, semicircular in outline when seen laterally. 
This is similar to the crest on the head of d¢twmida and curticauda 
but is relatively smaller. Head fused with the first segment, the 
resultant cephalothorax just exceeding the length of the rest of the 
metasome. The fifth segment is rounded or somewhat squarely trun- 
cated at the posterior corners and reentrant at the center dorsally. 
Urosome about one-fifth as long as the metasome and 4-segmented ; 
the genital segment is wider than long, with an asymmetrical process 
on the left side. Each of the three abdominal segments is also wider 
than long and they increase in length backward. The caudal rami 
are attached to the posterior corners of the anal segment, far apart 
and divergent, each with four setae, the outer one on the outer margin 
near the base of the ramus. There are two ovisacs, each cylindrical 
and two-thirds as long as the entire body, the eggs moderately large 
and irregularly arranged, 30 to 35 in each ovisac. 
The first antennae are slender and reach beyond the caudal rami; 
the exopod of the second antenna is nearly three times as long as the 
endoped and armed with very long setae (fig. 86). The chewing 
blade of the mandible has a long acuminate tooth at the inner corner, 
with four larger curved teeth and two smaller straight ones scattered 
along itsedge. The exopod of the first leg is 2-segmented, the endopod 
1-segmented ; the exopod of the second leg is 3-segmented, the endopod 
1-segmented; both rami of the third and fourth legs are 3-segmented. 
The first basipod of the fourth leg has a plumose seta on its inner 
margin and a single spine on its posterior surface. Total length 
5.86 mm. Metasome 4.90 mm. long 1.75 mm. wide. 
Male.—Metasome with the same general form as that of the female 
but a little smaller; head with the crest or helmet so reduced as to be 
easily overlooked; posterior corners of fifth segment evenly rounded. 
Urosome 5-segmented with the genital segment perfectly symmetrical 
and the abdominal segments longer than wide and diminishing in 
length backward. Caudal rami similar to those of the female but 
with longer setae. 
