676 CLASS x. 



quadrate, receiving the fourth joint at the internal angle of the 

 superior margin. External antennae with seta pretty long, sub- 

 ulate, with elongated joints, first joint large, grown to the shell, with 

 the external margin shutting in the orbit beneath. Shell mostly 

 longitudinally triangular, or oval, spinose, with rostrum bicornute. 

 Abdomen in most composed of seven segments. 



Pisa LEACH (and Lissa ejusd.). Add sub-genera : Hyas LEACH, 

 Mycippa LEACH, Leucippa EDW., Pericera LATR., Herbstia, EDW. 



Sp. Hyas araneus LEACH, Cancer araneus L., Cuv. R. Ani., ed. ill., Crust. 

 PI- 33 % t> BELL B rit ' Crust, p. 31. 



Maja LAM. (exclusive of several species). Add sub-genera : 

 Acanthonyx LATR., Chorinus LEACH, Mithra LEACH and some 

 others. Comp. DE HAAN 1. 1. pp. 81 83. 



Sp. Maja squinado LATR,, Cancer squinado HERBST, DESMAR. Crust. PI. 21, 

 BELL Crust, p. 39 ; on the S. and W. coasts of England, in the Mediter- 

 ranean, &c. 



Parthenope FABR. First pair of feet very long, geniculate at 

 the chela, remaining feet moderate, (Third joint of maxilliform 

 feet as in Maja.) Basal joint of external antennas not concrete 

 with shell, not closing the orbit. Shell mostly triangular, often 

 broader than long, tuberculate. Rostrum short. 



Parthenope FABR., LEACH (and Larabius LEACH). 



Sp. Parthenope horrida, Cancer horridus L., RUMPH. A nib. Rariteitk. Tab. 

 IX., DESMAR. Crust. PI. 20, fig. i ; from the Indian Ocean. 



(Ethra LEACH, LAM. 

 Cryptopodia EDW. 



Note. These sub-genera, scarcely distinct, differ from Parthenope in the 

 feet, as in Calappa, concealed under the shell. 



Family XXXIV. Cancrina (Arcuata and Quadrilatera LATR., 

 Catometopa and Cyclometopa EDW.). Space between the origin 

 of middle antennae and area of mouth short, transverse, much 

 broader than long. Shell never running anteriorly into a frontal 

 rostrum. 



A. Fourth joint of maxilliform feet placed upon the middle apex 

 or the external angle of third joint. 



Shell mostly subquadrate or trapeziform, with frons declining or 

 perpendicularly inflected. 



