ISOPODA. 



NORMALIA. 



j:ga psora. 



283 



^GA PSORA. 



Specific character. Oval and convex, coxise marked with two oblique lines ; 

 those attached to the four anterior segments square, those to the three poste- 

 rior segments subtriangular and distant from each other; terminal segment 

 of the pleon triangular, smooth on its ujiper side, with the lateral margin 

 slightly dilated ; inner plate of the lateral appendages emarginate near the 

 extremity of its outer edge. 



Length, I5 to nearly 2 inches. 



Oniscus psora. Pennant, Brit. Zool. vol. iv., pi. 18, f. 1, 1777 (certe). 



^Ega emarginata. Leach, Dictionn. Sci. Nat. xii. p. 349. Trans. Linn. 

 Soc. xi. p. 370. Suppl. Enc. Brit. 1, 428, pi. 22. 

 Samouelle, Ent. Compend. p. 109. Desmaeest, 

 Crust, p. 305, pi. 47, f. 4, 5. Milne Edwards, 

 Crust, iii., p. 240. Cuvier, Regne An. (Ed. Crochard), 

 Crust, pi. 67, f. 1. 



This species is distinguished at once by the somewhat 

 triangular form of the terminal segment of the tail, which 



