REPORT ON THE ISOPODA. 35 



any other species, but it can easily be distinguished by the smaller epimera and by the 

 shape of the caudal shield, which is more triangular than in that species ; as in Seroh'i:! 

 schythei, the caudal shield is traversed by three longitudinal carinse, and there is a stout 

 spine close to its anterior border in the middle line ; another carina runs parallel to 

 the anterior margin of the caudal shield, of which traces exist in Serolis schythei. The 

 transverse ridge of the latter is not found in Serolis paradoxa. As in Serolis schythei, 

 the first four free thoracic segments have their epimera separated from the terga by a 

 distinct suture. 



The antero-Iateral areas of the cephalic shield are more extensively developed in 

 Serolis paradoxa, so that the breadth of the anterior portion considerably exceeds that of 

 the posterior portion, while in Serolis schythei the transverse diameter of the cephalic 

 shield is greatest at about the level of the eyes. 



Antennce. — The filament of the second pair of antennae in both the male and female 

 is furnished with a series of short recurved hooks ; these hooks are not found upon all the 

 joints of the filament, they commence to be visible (in one specimen) on the seventh, 

 and extend as far as the sixteenth ; in the last nine or ten of these joints there is a 

 continuous row on the upper surface not far from the inner margin, commencing close to 

 the posterior articulation and extending in a straight line up to the anterior articulation, 

 the row of hooks then bends inwards and follows closely the anterior edge of the 

 joint, terminating at its outer extremity; in the anterior joints the hooks gradual^ 

 decrease in number until in the seventh joint there is only a short row on the anterior 

 margin. 



Similar structures are found in other species {e.g., Serolis bromleyana, Serolis gracilis, 

 Serolis septemcarinata, Serolis schythei), though in no case are the hooks so large and 

 conspicuous as in Serolis paradoxa. 



The inner lobe of thejirst maxilhe is nearly half the length of the outer lobe ; it con- 

 sists (PI. V. fig. 14) of a straight and narrow stem and an oval wider distal portion 

 furnished with a single spine near the lower border. 



The second pair of maxillce has, as in all other species, two smaller anterior lobes and 

 a larger posterior one ; the anterior lobe is a trifle smaller than the second, and bears 

 at its free extremity two long spines ; the second lobe has five or six, while the largest 

 posterior lobe has some twenty or thirty. 



The maxillipedes are characterised by the almost square outline of the stipes, which 

 is quite twice the breadth of the lamina ; the latter is clothed on the inner surface -with 

 fine hairs; the suture which separates it from the stipes is not complete posteriorly. 



The third pair of thoracic appendages in the male (fig. 13) are very much like those 

 of Serolis necera ; the second, third, and fourth joints are furnished with abundant 

 plumose hairs arranged in two rows, one above the other ; the upper row spring from 

 a strong ridge which runs at a short distance from the inner margin of these three 



