MARINE ISOPODA OF NEW ENGLAND, ETC. 379 



PLATES IX AND X, FIGS. 58-63. 



This species may be most readily recognized among our Isopoda by 

 the distinct thoracic and abdominal segments, the small lateral eyes, 

 and the evident distinction, in both autennula3 and antennae, of pedun- 

 cle and flagelluni. From the next species it is distinguished by the tip 

 of the telson, which is truncated, or slighty emarginate, and grooved on 

 the median line above near the end. 



The body is, when extended, about three times as long as broad, and 

 is smooth and polished throughout. The head is quadrate, a little broader 

 in front than behind, and embraced at the sides by the first thoracic 

 segment. The eyes are triangular, with the angles rounded, and are 

 often partially covered below by the projecting anterior lobes of the first 

 thoracic segment. They are separated by about three times their long- 

 est diameter. The antennuh^ (pi. X, fig. 60) are robust, with their 

 basal segments in contact; the first segment is short and sub-spherical; 

 the second also short ; the third cylindrical and as long as the first two 

 taken together and followed by a robust, but short, tapering flagellum, 

 consisting of about fifteen segments, of which the second is as long as any 

 other two, but the rest are all short. The flagellar segments beyond 

 the first are provided each with a tuft of " olfactory setae." The antennae 

 (pi. X, fig. 61 ) are longer and more slender than the antennula3, and 

 are separated at their bases. The first four peduncular segments are 

 robust ; the first two short ; the third and fourth each about twice as 

 long as the first or second, and the fifth or last peduncular segment 

 slightly the longest and much the most slender. The fourth and fifth 

 segments bear along the distal portion of their outer margins long 

 bristle-form hairs. The flagellum is slender and composed of from li> 

 to 18 segments, each bearing a few short bristles. The maxillipeds 

 (pi. X, fig. 62 ) are elongated and almost pediforin but flattened ; 

 the external lamella is small and subtriangular, rounded and hairy at 

 the tip ; the palpus is five-jointed, with the last four segments broad, 

 flattened, and well ciliated ; the tip of the maxilliped, nearly concealed 

 by the large palpus, is provided with very densely plumose bristles. 

 The outer maxillaB (pi. X, fig. 61 b) are short and robust ; the two articu- 

 lated lobes narrow ovate, rounded at the tip, armed, especially the inner 

 one, with spines and plumose or pectinated bristles. The inner maxillte 

 (pi. X, fig. 61 c) are robust, with the outer lobe armed with strong smooth 

 spines ; the inner lobe rounded at the end and bearing three straight 

 rather blunt spines, densely covered toward the tip with soft hairs. 

 The mandibles (pi. X, figs. 61 d) are robust and horny at the tip, armed 

 with one strong acute tooth, and in the right mandible with one acute 

 and one obtuse tooth along a cutting edge, while the left mandible has 

 three less acute teeth along this edge. Each mandible is, moreover, 

 provided with a molar process or area (w), on its inner surface set along 

 its interior and upper margin with spines. A narrowly lanceolate leaf- 

 like appendage is attached just below the molar area. This appendage 



