MARINE ISOPODA OF NEW ENGLAND, ETC. 395 



This genus is represented by a single species, in which the body is of 

 a broadly oval form and depressed. All the legs are short and armed 

 with strongly curved dactyli, and, in the natural position, are closely 

 appressed to the ventral surface, which, however, is more or less exposed 

 below along the middle. 



Livoneca ovalis White (Say). 



Cymothoa ovalis Say, Jour. Acad. Nat. Sci. Phil., vol. i, p. 394, 1818. 



Dekay, Zool. New York, Crust., p. 48, 1844. 

 Livoneca ovalis White, Cat. Crust. Brit. Mus., p. 109, 1847. (Lironeca). 



Harger, This Report, part i, p. 572 (278), pi. vi, fig. 29, 1874 ; Proc. U. S. 

 Nat. Mus. , 1879, vol. ii, p. 1G2, 1879. 



Plate XI, Fig. 67. 



The broadly oval, more or less distorted and unsymmetrical form of 

 this Isopod serves to distinguish it from any other species yet recog- 

 nized within our limits. 



Body broad, oval, usually oblique, and not, as represented in i^art I 

 of this report, pi. VI, fig. 29, with the sides of equal length. The legs, 

 moreover, in that figure are in an unnatural position, as they are, dur- 

 ing life, concealed beneath the body of the animal and appressed to the 

 ventral surface, the first three iiairs directed forwards and the last four 

 pairs backward. The dorsal surface is moderately convex. The head is 

 small, rounded in front, trilobed behind, the middle lobe much the larg- 

 est, the two lateral lobes extending beyond the eyes, which are not con- 

 spicuous, small and broadly separated. Antennulse (pi. XI, fig. G7a) 

 widely separated at the base, with the first segment short and stout ; the 

 second longer and somewhat tapering; the third about as long as the 

 first. These peduncular segments are somewhat flattened. The flagel- 

 lum is longer than the peduncle, tapering and five-jointed, curved back- 

 ward in the natural position, each segment bearing a row of short blunt 

 setae, near the distal end, on the inner curve. The antennae (pi. XI, fig. 

 676) are about as long as the antennuhe, with the first two segments 

 short and stout, the next three more slender; flagellum three or four 

 jointed, with the last segment imperfectly divided and tipped with a 

 few short setae. The maxillipeds are narrow, with the outer lamella 

 partially united to the basal segment and the palpus tai^ering and two- 

 jointed, tipped with a few short curved setae, at least in young individ- 

 uals. The mandibles are pointed; their palpi (pi. XI, fig. 67 c) tapering 

 from the base and comjjosed of three segments of about equal length, the 

 first subquadrate, the second tapering, the third nearly cylindrical. 



The first thoracic segment is longest ; the next three a little shorter 

 and about equal ; the fifth and sixth still shorter ; the seventh shortest 

 measured along the median line, which is usually a curved line except 

 in young specimens. The anterior margin of the first thoracic seg- 

 ment is adapted to the posterior margin of the head and presents three 

 sinuses, the middle one largest, for the median lobe of the head, and two 

 smaller ones for the ocular lobes. The posterior margin of this segment 

 is strongly convex backward throughout. In the succeeding segments 



