MARINE ISOPODA OF NEW ENGLAND, ETC. 395 



Tliis genus is represented by a single species, in which Hie body is of 

 a broadly oval form ami depressed. All tin; Nigs ;ini short and armed 

 with strongly curved daefyli, and, in the natural posit ion, an-, closely 

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

 below along the middle. 



Livoneca ovalis Wliito (Say). 



Cymothoa ovaUe Say, Jour. Acad. Nat. Sci. 1'hil., vol. i, p. if'.M, 1818. 



DcUiiy, Zool. New York, Cnmt., p. <1H, 18-14. 

 Livoneca ovaUs "White, Cat. CriiHfc. Brit. MIIH., p. 101), 1847. (lAnmcca). 



llargcr, This Rcporf, purl i, p. 572(278), pi. vi, lig. 29, 1874; Proc. U. 8. 

 Nat. MUH., 1871), vol. ii, p. 102, 187'J. 



PLATE XI, Fi<;. (\1. 



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

 this Isopod serves to distinguish it from any other species yet rccog 

 ni/ed within our limits. 



Body broad, oval, usually oblique, arid not, as represented in part I 

 of this report, pi. VI, fig. 21), with the, sides of equal length. The, legs, 

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

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

 ventral surface,, the first three pairs directed forwards and the hist 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- 

 spieuoiis, small and broadly separated. Antennnhe (pi. XI, fig. <>7) 

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

 Keeond longer and somewhat lapering; flu; third about as long as the 

 first. These peduncular segments are somewhat flattened. The, llagel- 

 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 

 sct:e, near the distal end, on the inner curve,. The antenna) (pi. XI, fig. 

 (57/>) are about as long as the, antennuhc, with the first two segments 

 short and stout, the next three more slender; (lagellnm 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 tapering and two- 

 jointed, tipped with a few short curved set:e, at least in young individ- 

 uals. The mandibles are pointed; their palpi (pi. XI, fig. 07 c) tapering 

 from Hie base and composed 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, t he 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 segment^ 



