MARINE ISOPODA OF NEW ENGLAND, ETC. 401 



ciliated along its free superior margin. The first pair of pleopods 

 (pi. XI, fig. 68 e) are composed on each side of a short, quadrate basal 

 segment supporting two rami, of which the outer is, like the basal seg- 

 ment, of firm texture, and acts as an operculum ; in shape it is semi- 

 oval, with the inner ma'rgin nearly straight, and is ciliated distally, and 

 along the outer margin. The inner ranius is much smaller than the 

 outer and of delicate texture, and, in the natural position, is covered and 

 concealed by the outer ramus; it is slender, with nearly parallel sides, 

 rounded at the tip, and not ciliated. In the males the second pair 

 of pleopods (pi. XI, fig. 68/) bears, near the middle of the inner margin 

 of the inner ramus, a slender stylet, slightly surpassing the lamella to 

 which it is attached. 



The lamellae forming the incubatory pouch of the females are of con- 

 siderable antero-posterior dimensions, and the posterior widely overlap 

 the anterior ones, while the anterior border of the first lamella is united 

 with the third thoracic segment, to which the lamella belongs. 



Length 15-18 mm ; breadth 1.8-2 mm . The color is brownish above, 

 mottled with yellowish or honey color, lighter underneath. 



This species was described as new by the present author in the first 

 part of this report under the name A. brunnea, but there appears to 

 be no sufficient reason for regarding it as distinct from Dr. Stiinp- 

 son's A. polita. It is apparently closely related to A. gracilis Leach, 

 although sufficiently distinct according to Bate and Westwood's* de- 

 scription and figures. Those authors, however, seem to have had but 

 very poor and imperfect material on which to base their work. They 

 figure and describe the telson and uropods as truncated and crenulated, 

 and Montagu,t in his original description of the species, says that " the 

 body is terminated by five large caudal appendages truncated at their 

 ends." 



Kroyer's $ descriptions and figures of A. carinata approach much more 

 closely to the present species. His figure of the antennula considerably 

 resembles ours, but in his description he gives as the relative lengths 

 of the four segments composing it 11, 4, 3 7 5. In our species the last or 

 flagellar segment is much the shortest, as may be seen by the figure, 

 plate XI, fig. 68 a. He further speaks of the telson as crenulated, while 

 it is entire in A. polita, and his figure (Voy. en Scand., pi. 27, fig. 3n') 

 shows no tooth-like projection or angle on the basal segment of the 

 uropods, as seen in a lateral view, and the corresponding margin of the 

 outer or superior plate is destitute of the notch shown in the lateral 

 view of these organs on plate XI, fig. 68 g. The inner ramus or lamella 

 of the first pair of pleopods is also figured as much larger and more 

 expanded distally than in our species, for which see plate XI, fig. 68 e. 

 Unfortunately I have had no European specimens for comparison. 



*Brit. Sess. Crust., vol. ii, p. 160, 1868. 

 t Trans. Linn. Soc., vol. ix, p. 103, pi. v, f. 6, 1808. 



tNaturhist. Tidssk., II, B. ii, p. 402, and Voy. en Scand., Crust., pi. xxvii, fig. 3a-0, 

 1849. 



26 F 



