178 CRUSTACEA. ISOPODA. 



OKDER V. ISOPODA. 



Head distinct ; mandibles without palpi ; three pairs of jaws, 

 the inferior appearing like two small feet united at their base, 

 or a lip with two palpi ; body more or less depressed, divided 

 into segments, varying from three to seven ; ten or fourteen 

 feet ; tail formed of from one to seven or more segments, bear- 

 ing branchiae, and often covered with laminae or leaflets ; no 

 shell ; eyes granulated ; antennae generally four. 



SECTION I. AQUATICA. 



With four distinct antennae, the anterior with at least three or 

 four joints ; or destitute of antennae ; inferior appendages of 

 the post-abdomen generally vesicular, and without particular 

 openings for the entrance of air. 



In this section the appendages of the belly are longitudinal and nearly similar in 

 both sexes. The peduncle of the antennae is generally multiarticulate. The greater 

 portion of the Crustacea of this division live upon fishes, attaching themselves to their 

 bodies by means of their feet, which are terminated by strong hooks. 



FAMILY I. EFICARIDES. 



Body much flattened above, concave below, for containing the 

 ova ; destitute of eyes, antennas, mandibles, and caudal fin. 



Gen. 1. BOPYRUS, Lat. Monoculus, Fab. 

 Body ovoid, depressed, soft, with a strong longitudinal projec- 

 tion above ; head oblique, distinct ; tail flattened, oblique, 

 narrower than the body, marked with transverse wrinkles ; 

 no eyes or antennae, fourteen small feet. 



What is conceived to be the male in this genus is an extremely small animal, 

 with a distinct head, two black round eyes, and body formed of six or seven rings. 

 They always accompany the females. 



B. squillarum, Lat. (M. crangorum, Fab.) Body flat, pale whit- 

 ish. 4 lines long. Parasitical upon the bodies of the Alphei and 

 Palaemones. Lat. Hist. vii. pi. 59, fig. 2-4. 



The resemblance of this little animal to a sole has induced the belief among fish- 

 ermen of its being a young sole in the first stage of its existence. Its presence under 

 the shell of the animal on which it is parasitical always produces a protuberance. 



FAMILY II. CYMOTHOADES. 



With four antennae and eyes, sometimes indistinct ; mandibles 

 horny ; feet of the ordinary form, and proper for walking and 

 prehension ; and a fin on each side at the posterior extremi- 

 ty of the body ; post-abdomen of from four to six segments. 

 Gen. 2. CYMOTHOA, Leach. 



Head narrower than the body ; last joint of the abdomen square, 

 pointed or rounded ; laminae of the ventral segments in the 

 form of styles, almost equal ; segments of the body angular 

 on the sides, and rounded posteriorly ; eyes obsolete. 



