ORDER DECAPODA. 149 



Such are, 



PODOPHTHALMUS, Lam. 



The test is in the form of a transverse trapezium, more 

 broad and straight in front, with a long tooth in the form of a 

 spine, behind the ocular cavities. The claws are elongated, 

 spiny, and similar to those of the majority of the species of the 

 genus Lupa of Dr. Leach. The only living species known 

 inhabits the coasts of the Isle of France, and those of the 

 neighbouring seas. 



The ocular pedicles of the other Crustacea of this section 

 are short, occupy but a very small portion of the transverse 

 diameter of the testa, lodge in oval cavities, and resemble in 

 general those of the ordinary crabs, with which those swim- 

 ming Crustacea are almost insensibly connected. 



These Crustacea may be united into a single subgenus, 

 that of, 



PoRTUNUS, Fab. 



Some species proper to the seas of the East Indies, such 

 as the Admetus of Herbst, are distinguished from all the fol- 

 lowing by their testa in the form of a transverse quadrilateral 

 figure, narrowed posteriorly, and whose ocular cavities oc- 

 cupy the anterior lateral angles. The eyes are thus distant 

 one from the other, by an interval almost equalling the greatest 

 breadth of the testa. The insertion of the lateral antennae is 

 very remote from these cavities. 



Other species, whose testa is in the form of the segment of 

 a circle, truncated posteriorly, and wider in the middle, are 

 remarkable for the length of their claws, which is at least 

 double that of the testa. Its sides present each nine teeth, 

 of which the posterior one is much larger, in the form of a 



