ORDER DEC APOD A. 
173 
Calappa, Fab., 
Have the testa very gibbous, the forceps triangular, very 
much compressed, denticulated above, like a ridge or crest, 
and covering perpendicularly the front of the body, when the 
feet are contracted. The third articulation of the external 
jaw-feet is terminated like a hook ; the superior extremity of 
the buccal cavity is narrowed, and divided longitudinally into 
two lodges by a partition. 
Some, and the most numerous, have the two posterior and 
lateral dilatations of the testa incised, and denticulated. ( Can- 
cer granulatus, Linn., Calappa granulata, Fab.) 
Others, such as Calappa fornicata, Fab., have the edges 
of the dilatations of the testa entire. 
iETHRA, Leach, 
Differ from calappa, by their very flatted testa, their forceps 
not raised perpendicularly, nor shading the front of the body, 
and the almost square form of the third articulation of the ex- 
ternal jaw-feet. 
Sometimes, ( JElhra depressa, Lam.) the testa is in a trans- 
verse oval ; sometimes , (Parthenope fornicata, Fab.) in the 
form of a short triangle, very broad, dilated, and rounded 
laterally. The claws are but little elongated, and tolerably 
thick ; but sometimes they are longer, angular, and remind us, 
as does also the form of the testa, of the parthenopes. These 
last species might form a subgenus proper. 
Finally, a seventh and last division, Notopoda, is formed 
of brachyuri, whose last four, or last two feet, are inserted 
above the level of the others, or seem to be dorsal and turn 
upwards. In those in which they are terminated by a sharp 
hook, the animal usually employs it to retain divers marine 
