PROCEEDINGS OF UXITED STATES NATIONAL MUSEmi. 5 



prominence usually bears a single sliort hair. The superior autenuce 

 are short and three-jointed, the last joint being beset with a few audi- 

 tory hairs. In the male both pairs of antenuiTe are present, and are 

 provided with long, flexible llagella; the last joint of the peduncle of 

 the superior pair long, as in the female, but much more robust, and 

 densely furnished with hairs; the peduncle of the inferior pair three- 

 jointed. The abdomen of the male is stouter, and the bases of the 

 swimming feet more nearly rounded; in the female the basal portion of 

 these feet are oblong-ovate, and the last segment of the thorax is longer 

 and narrower than the corresponding part in the male. 



Phronima atlantica, Gueriu. 



(Plate I, Fig. 1, la, 2.) 



Phronima atlantica, Gu^rin-Meneville, Iconogr., pi. 25, fig. 4; Mag. Zool., 1836, cl, vii, 

 pi. 18, fig. 1,— Milue-Edwards, Hist, des Crust., 1840, iii, p. 93.— C. Speuce 

 Bate, Catalogue Ampbi. Crust., 1862, p. 319, pi. 51, fig. 4.— Daua, U. S. 

 Explor. Exped., 1852, p. 1001. 



Female. — The first and second joints of the peduncle of the superior an- 

 tenme S'hort; the last more than twice the length of the first two. The 

 first and second i)airs of thoracic feet with the carpal joint jjroduced an- 

 tero-inferiorly, and the produced portion evenlj^ set with sharp spines 

 along its anterior edge; the following joint, which antagonizes with the 

 produced portion of the preceding, slightly arched and spinous along its 

 inferior edge; the last joint notched below the end, and furnished with 

 a ribbed, pectinated appendage on either side of its base; the third joint 

 prolonged anteriorly below, truncated, and set around with short, sharp 

 bristles or spines. The second pair of legs longer than the first. The 

 third and fourth pairs with the basal joint armed behind, at its ex- 

 tremity, with a sharj) spine ; the basal joint of the fifth pair armed in 

 the same manner as the two preceding, but the spine is mnch larger in 

 the former; there is likewise a spine on the middle of the following 

 joint, in front. The third joint of the fifth pair enlarged, arched above, 

 and lengthened; the fourth joint, or palm, long, attenuated at its articu- 

 lation with the third, and gradually broadening to its junction with the 

 fifth joint, arched above, the inferior angle produced anteriorly into a 

 long and stout i)oint, corresponding to the immovable finger of the 

 Cancridw, the anterior border with two stout, ]irominent teeth, the 

 upper the larger, tuberculated on the edge towards the movable finger, 

 and beset with a few bristles or hairs; the fifth joint, or movable finger, 

 longer than the anterior border of the palm, arched above, and with a 

 broad prominence on the middle? of the inferior margin; the last joint 

 very small, and in old subjects fused with the preceding joint. The 

 basal joint of the sixth and seventh pairs of legs armed at the ex- 

 tremity, in front, with a short spine; and the second and third joints of 

 the last pair with a prominent, rounded projection on the anterior 

 surface, that on the second joint more pointed. The first pair of caudal 

 appendages extending almost as far backward as the extremity of the 



