ORDER DECAPODA. 
155 
Trapezia, Lair ., 
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 claw’s very large, in 
comparison with the other feet. Cancer cymodoce , &c. all 
exotic. 
Pilumnus, Leach , 
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, Lair ., 
With 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 
