MARINE ISOPODA OF NEW ENGLAND, ETC. 399 



The body is smooth, shining and flattened above and broadly keeled, 

 in the males below. The head is a little broader than long, deeply ex- 

 cavated on each side of the front for the bases of the antennulae, and 

 produced at the sides. The eyes are small and lateral but distinct, and 

 are placed on the outer side of the anterior prolongations of the head, 

 about on a line with the bases of the autennula3. They are too indistinct 

 in the figure, and the eye was even omitted on the right side by the en- 

 graver. The antennulae (pi. XI, fig. 68 a) consist of a tapering three- 

 jointed peduncle and a very short flagellurn. The first peduncular seg- 

 ment is the largest, and is flattened above and on the inner side ; the 

 second segment is smaller, cylindrical, and provided with a comb of hair- 

 like seta3 along its outer side ; the third is smaller and shorter than the 

 second; the flagellum consists of a single very small segment, with 

 indications of a rudimentary second segment at the end, where it is also 

 tipped with setae. The antennae (pi. XI, fig. C86) consist of a five-jointed 

 peduncle, and a short flagellum much like that of the antennulae. The 

 basal segment of the peduncle is short; the second segment is the 

 largest and is of peculiar shape, being excavated on the outer side to 

 adapt it to the antennula. which lies in the groove thus formed, while 

 the segment is bent upward and inward, and exposes a slender triangu- 

 lar area' with the point backward, between, and on a level with, the an- 

 tennulae ; the next three segments are sub-cylindrical and diminish in 

 size, and are followed by one or two small flagellar segments tipped with 

 setae. 



The maxillipeds (pi. XI, fig. 69a) are thick and strong, and are com- 

 posed of a basal quadrate segment, a Little longer than broad, with its 

 proximal external angle elided for the short, sub-triangular external 

 lamella, and bearing two segments representing the palpus. Of these 

 segments the first is but little smaller than the basal segment and 

 is sub-quadrate, tapering a little at the sides beyond the middle. The 

 terminal segment is straight at its articulation with the preceding, and 

 nearly so along the inner side, then rounded in the remainder of the out- 

 line. The segments of the palpus are finely ciliated along their margins, 

 except along the external margin of the first segment, where the cilia- 

 tion nearly disappears ; they are also provided with coarse setae, a few 

 of which occur on the maxilliped, near the outer distal angle. The inner 

 maxilla (pi. XI, figs, 69 & and &') is rather robust, and terminated by 

 a strong tooth or spine, below which, on the inner side, is a row of 

 smaller curved teeth. The mandibles are terminated by a horny tooth, 

 below which is a serrulated lobe ; the mandibular palpus is robust ; the 

 second segment much the longest and provided with stout setae ; the last 

 segment with a comb of rather short setae. The maxillipeds are of much 

 firmer texture than the other parts of the mouth. 



The first thoracic segment is the longest, and is closely adapted to 

 the head behind so as to allow but little motion. The second segment 

 is shorter but somewhat broader than the first, and is rather freely 



