COPEPODS GATHERED BY ALBATROSS—-WILSON 153 
Remarks.—A. hamata differs from all the other species of the genus 
in the presence of the large spines on the basal segments of the an- 
tennae of the female. These stand out so prominently that they serve 
to identify the species at a glance. 
ACARTIA LAXA Dana 
PLATE 20, FIGURES 267-269 
Acartia lara Dana, Proc. Amer. Acad. Arts and Sci., vol. 2, p. 26, 1849; United 
States Exploring Expedition, 1838-1842 (Wilkes), vol. 14, pt. 2, Crustacea, 
p. 11238, 1853; pl. 79, fig. 5 a-c, 1855. 
Stations 5171; 5175; 5208; 5209; 5231. This was one of the new 
species described and figured by Dana in the Wilkes plankton from 
female specimens collected in the Sulu Archipelago in the Straits 
of Banca. Brady reported it in the Challenger plankton from the 
Philippine Islands and gave a description of the female with 11 
figures. It does not appear in any of the other plankton lists, al- 
though T. Scott (1894, p. 65) found it to be of frequent occurrence in 
38 tow nettings from the Gulf of Guinea. In spite of these descrip- 
tions and figures it has remained a questionable species with the male 
unknown. The Albatross material includes both sexes. My descrip- 
tions of them validate Dana’s species. 
Female.—Metasome elongate-elliptical, three and a half times as 
long as wide and narrowed a little anteriorly and posteriorly. Head 
fused with the first segment and obtusely rounded on the frontal 
margin; fourth and fifth segments fused and a little concave pos- 
teriorly, with stout spines at the corners which reach beyond the 
center of the genital segment. Urosome less than a third as long 
but more than a third as wide as the metasome, tapered regularly 
backwards, and 3-segmented. Genital segment somewhat trapezoidal 
in shape, being narrowed a little posteriorly, with straight sides. The 
two abdominal segments are the same width and length and combined 
are longer than the genital segment. The caudal rami are twice as 
long as wide, each armed with five plumose setae, which are so diver- 
gent that the flabellum or fan which they form is actually wider 
than long. 
The first antennae are a little longer than the body and stand out 
on each side in the same straight line at right angles to the body axis. 
The endopod of the second antenna is about five times as long as the 
exopod, and the segmentation at the tip of the latter is invisible. The 
mandible has a large outer acuminate tooth separated from the others, 
and a row of seven smaller saw-teeth across the end, diminishing in 
sizeinwardly. The first four pairs of legs are similar to those in other 
species of the genus, the fifth pair being quite slender and 2-segmented. 
The second segment is more than twice as long as wide and is tipped 
