40 Richardson — Description of a New Parasitic Isopod. 



pair less so, and the propodns of this, pair is furnished with a large cultri- 

 form process. Five spines are present on the merus 

 of all three pairs. Gressorial legs slender and sparsely 

 spinulose. 



All the abdominal segments are visible in a dorsal 

 view. Terminal segment broad and posteriorly In- 

 sinuated, forming three teeth with rounded extremi- 

 ties ; its surface entirely smooth. 



Outer branch of uropods narrower and somewhat 

 shorter than the inner branch ; its extremity is 

 rounded. Inner branch obliquely truncate and crenu- 

 late on posterior margin. Uropods and terminal ab- 

 dominal segment all fringed with a few hairs. 



Two individuals of tins species were found — one be- 

 tween the delta of the Mississippi and Cedar Keys, 

 Fig.2.— Mga eearinata Florida, Station 2401), depth SS fathoms; the other, 

 (X53). the type (No. 21001, U. S. Nat. Mus.), oft' Little Ba- 



re. Leg of 1st pair. hania Bank, Station 2655, depth 338 fathoms. 



b. Leg of 3d pair. This species is closely related to .1. tridens* Leach, 



c. Leg of 7th pair. ". . . . 



but presents many specific differences: in the relative 



length and breadth of the body, the length being more than three times 

 greater than the breadth in A. eearinata, while in A. tridens Leach the 

 length is only two and one-half times greater than the breadth; in the 

 number of joints in the 1st and 2d pairs of antenme, ten in the 1st pair 

 and nineteen in the 2d pair being characteristic of A. tridens Leach, 

 nine in the 1st and ten in the 2d pair being true of our species ; in the 

 presence of a cultriform process on the propodus of the third pair of pre- 

 hensile legs, which process is entirely wanting in A. tridens Leach ; and 

 in the perfectly smooth surface in the present species of the terminal 

 segment of the abdomen, which in the other species is tricarinated. 



* For synonymy, see Naturhistorisk Tidsskrift, vol. XII, 1879-'80, 

 Schicedte & Meinert, 'Symbolsead Monographiura Cymothoaruin, Crus- 

 taceorum Isopodum Familise,' p. 340-341. 



