2S4« ^^g^ monophthdlma, 



the mouth is situated, armed with a pair of jaws, and fur- 

 nished with two filiform palpi, one on each side, quadriar- 

 ticulate ; the last joint unguiculate. Segments of the body 

 seven, subequal, marked with a faint line across the middle, 

 the margin pale; segments of the tail six, the first five 

 narrow, equal, transverse ; the terminal one broad, oblong, 

 roughish, depressed, with a strong keel down the centre, 

 ending in a short point or mucro : the margins of these seg- 

 ments are minutely spinous. On each side of the segments 

 of the body there is a strong movable process, pointed pos- 

 teriorly, and with two slight ridges down the middle : these 

 processes or coxae cover and serve for the insertion of the 

 legs, of which there are seven pairs. Legs white; the first 

 three pairs unlike the others, and directed forwards ; the 

 thigh thick, elongate, with a circular curved head moving in 

 an acetabulum; the tibia short, and smaller; the tarsus 

 3-jointed, with a strong curved claw : thigh of the posterior 

 pairs elongate, thickish ; the four succeeding joints much 

 more slender, almost equal, spinous, and terminated with a 

 curved claw. The legs are all punctured in the manner of 

 the body ; but the ventral surface of the segments is smooth. 

 Each caudal segment is furnished on each side with a pair of 

 broad oval membranous plates, ciliated on the margins, and 

 articulated, by twos, to a compressed stalk ; and there is, on 

 each side of the last segment, an additional pair of foliaceous 

 plates jointed to a movable, acutely-pointed, somewhat trian- 

 gular process. Of these plates, the inner is wedge-shaped, 

 the other oblong; and both are densely ciliated round the 

 edge. 



This description is taken from the larger specimen figured 

 (flr, dorsal aspect; b, ventral aspect) ; the smaller one {c) differs 

 in having the two inferior joints of the superior antennae not 

 disproportionately enlarged ; and the large segment of the 

 tail is emarginate, truncate, with a shallow furrow down the 

 centre, and two obtuse raised keels at its sides. In other 

 respects, I perceive no difference. The figures are of the 

 natural size. 



JE'ga monophthalma swims with rapidity by the aid of its 

 caudal fins ; and, when it comes in contact with a solid body, 

 it claps against it, and adheres tenaciously. Our specimens 

 were taken adhering to large codfish, of which, it is pro- 

 bable, they are the " pedicular " parasites ; but, unlike some 

 of their race, they seem to be very rare, at least in our bay, 

 for I could only procure three specimens ; and our fishermen 

 had never observed them before. 



