ORDER ISOPODA. 217 



Serolis, Leach. 



But one kuovvn species, Cymothoa paradoxa, Fab. The an- 

 tennae are placed on two lines, and terminated by a pluri- 

 articulate stem. Under the three first segments of the tail, 

 between the ordinary appendages, there are three others, trans- 

 verse, and terminated posteriorly in a point. 



Sometimes the eyes are lateral, and not carried upon tu- 

 bercles. The tail is composed of five or six segments. 



Here the eyes are not comj)osed of simple eyes approxi- 

 mated, and in the form of little grains. The antennae are on 

 two lines, and of seven articulations, at the least. The six 

 anterior feet are commonly terminated by a strong claw. 



In some, whose tail is always of six segments, the length 

 of the lower antenna? never exceeds half that of the body. 



We shall commence with those whose mandibles, as is most 

 usual, project but little, or not at all. Here come the 



Cymothoa, Fah., 



Whose antennae are almost of equal length, the eyes but 

 little apparent, with the last segment of the tail in a trans- 

 verse square, and the two pieces terminating the lateral fins, 

 linear and equal, in the form of a stylet. {Cymothoa oestrum. 

 Fab.) 



TCHTHYOPHILUS, Latr. {Nerocila Livoneca, Leach.) 



Having also the antennee of equal length, and the eyes but 

 little visible ; but the last segment of the body is almost trian- 

 gular, with the two pieces terminating the lateral fins, in the 

 form of leaflets or laminae, the exterior of which is larger in 

 Nerocila, and of the same size as the other in Livoneca. 



In the four following subgenera the upper antennae are ma- 

 nifestly shorter than the lower. 



Many have, like Cymothoa, all the feet terminated by a 



