156 CLASS CRUSTACEA. 



widened in fiont, as well as by their ocular pedicles, which, 

 like those of podophthalmus, are inserted near the middle of 

 the front, long, slender, and reaching the anterior angles ; the 

 claws of the males are long and cylindrical. Such are 



GoNOPLAX, Leach, 



Our seas furnish two species, Cancer angulatus, Linn., and 

 Cancer rhomhoides, Ejusd. ; the principal difference between 

 which is, that the former has spines at its anterior and poste- 

 rior angles, the letter at the anterior only. 



In the second division of quadrilatera, the fourth articulation 

 of the external jaw-feet, or of those which cover inferiorly 

 the other parts of the mouth, is inserted at the middle of the 

 end of the preceding articulation, or more externally. 



Sometimes the testa is trapezoid or ovoid, or in the form of 

 a heart, truncated posteriorly ; the ocular pedicles, inserted at 

 a little distance from the middle of its anterior edge, extend 

 as far as the anterior angles, or even go beyond them. 



In commencing with those whose testa has the form of a 

 transverse four-sided figure, widened in front and narrowed 

 behind, or has the form of an egg, we first find 



Macrophthalmus, Leach. 



As well as in gonoplax, the testa is trapezoid, the claws are 

 long and narrow ; the ocular pedicles are slender, elongated, 

 and lodged in a groove, under the anterior edge of the testa ; 

 the first articulation of the intermediate antennge is rather 

 transverse than longitudinal, and the two divisions which ter- 

 minate it are very distinct and of middle size ; the external 

 jaw-feet are approximate inferiorly at the internal edge, with- 

 out vacancy between them ; and their third articulation is 

 transverse. 



