MARINE ISOPODA OF NEW ENGLAND, ETC. 365 



(pi. IX, fig. 52 a., m') is quadrate, scarcely ciliated at the apex, and 

 distinctly articulated with the maxilliped. The outer maxilla} (pi. lX r 

 fig. 52 b) are three-lobed and strongly ciliated. The inner maxillae 

 (pi. IX, fig. 52 c) are two-lobed, the lobes robust and short, the outer 

 armed with short spines at the apex, the inner with three slender curved 

 setse. 



The thoracic segments are coarsely granulated or tuberculated ; the 

 first is produced at the sides around the head nearly to the eyes ; the 

 others have their anterior and posterior margins transverse. The fourth 

 segment in the female is a little less than three times as long as broad, 

 and is longer than the other six segments taken together, but is only 

 four-fifths as long as the last three segments together with the pleon. 

 It is tuberculated, especially above, but bears no prominent tubercles or 

 spines, and is subcylindrical. In the male this segment (pi. VIII, fig. 48 b) 

 is more elongate and much more slender, exceeding in length the three 

 following segments with the pleon. In the ordinary position the thorax 

 is geniculate at the posterior articulation of the fourth segment, forming 

 nearly a right angle with the rest of the body. The last three segments 

 have their epimeral regions angulated and salient. The first pair of 

 legs (pi. VIII, fig. 49 b) are of moderate length and, beyond the basal seg- 

 ment, flattened ; the basal segment is directed backward but the leg is 

 bent upon itself at the ischiuin and the remaining segments are directed 

 forward and applied to the under surface of the head. The ischium and 

 merus support but few cilia, and these mostly along their inner margins, 

 but the carpus, propoclus, and dactylus are not only ciliated on the in- 

 ner margin with slender simple cilia, but also bear on the side toward 

 the body stout scattered spinulose setse, which are specially abundant on 

 the propodus. The opposite side of the leg is nearly smooth. The sec- 

 ond, third, and fourth pairs of legs are five-jointed and similar to each 

 other, except that the basal segments of the second and third are some- 

 what shorter than in the fourth (pi. VIII, fig. 50). The second pair is 

 shorter than the third, and the fourth is a little the longest. All these 

 legs are directed strongly forward and habitually held nearly in the 

 position shown in the figure, under the anterior surface of the body and 

 the head. The last three segments are furnished with elongated setae 

 along their inner margins. These seta3 are inserted in two rows and so ' 

 placed as to diverge at an open angle. The dactyli appear to be obsolete 

 in these legs. The fifth, sixth, and seventh pairs of legs are of quite a 

 different and more ordinary structure. They contain the full number of 

 segments, and are terminated by robust, slightly curved dactyli. A 

 young specimen obtained has only two pairs of legs of the ordinary form, 

 the last or seventh pair being represented only by rounded tubercles, 

 one on each side of the seventh segment. 



The pleon is elongate-ovate, narrower in the male (pi. VIII, fig. 48 c). 

 Dorsally it is strongly convex, especially in front. It is two-thirds as 

 long as the fourth thoracic segment in the female, and three-fifths as 



