ORDER DEC APOD A. 155 



Trapezia, Latr., 



Similar to Eriphia, in the insertion of the lateral antennae, but 

 whose testa is almost square, depressed, smooth, with the eyes 

 situated at its anterior angles, and the claws very large, in 

 comparison with the other feet. Cancer cymodoce, &c. all 

 exotic. 



PlLUMNUS, Zmc/?, 



Different from the two preceding subgenera, by reason of their 

 lateral antennae being inserted at the internal extremity of the 

 ocular cavities, below the origin of the pedicles of the eyes ; 

 they are more approximate, as to the form of the testa, to the 

 Crustacea of the preceding section, than the other quadrilatera, 

 and ambiguous, in this respect, between the two sections. As 

 in the majority of the arcuata, the third articulation of their 

 jaw-feet is almost square or pentagonal ; the lateral antennae 

 are longer than the ocular pedicles, with a setaceous stem, 

 longer than the peduncle, and composed of a great number of 

 small articulations ; the tarsi are simply furnished with hairs. 



Thelphusa, ZrtYr., 



AVith lateral antennae, situated as in the pilumni, but shorter 

 than the ocular pedicles, of but few articulations, with the 

 stem scarcely longer than the peduncle, and cylindrico-conical ; 

 the testa is almost in the form of a truncated heart, and the 

 tarsi are furnished with spiny or denticulated ridges. Can- 

 cer Jluviatilis of Belon-Rondelet, and Gesner. 



Other quadrilatera, having, like the preceding, the fourth 

 articulation of the exterior jaw-feet inserted at the internal 

 extremity of the preceding articulation, are removed from 

 them by the trapezoidal form of the testa, transverse and 



