i <30 
CLASS CRUSTACEA. 
Gecarcinus, Lcitr., 
Whose four antennae are covered by the hood ; the second and 
third articulation of the exterior jaw-feet are large, flatted, as 
it were foliaceous, arched, and leaving a vacancy between 
them on the internal side ; or the last of these articulations is 
in the form of a curvilinear triangle, obtuse at the summit. It 
reaches the hood, and covers the three following articulations 
(4, 5, and 6.) Cancer rnricola , Lin. 
Sometimes the testa is almost square, subisometrical, or blit 
little broader than long, flatted, with the front diminished in 
almost its entire breadth ; the ocular pedicles are short, and 
inserted at the lateral anterior angles ; the two ordinary divi- 
sions of the intermediate antennae are very distinct ; the ex- 
ternal jaw-feet are separated internally, and form by this 
separation an angular vacancy ; their third articulation is 
almost as long as broad ; the claws are short and thick, and 
the other feet are very much flatted ; the fourth pair, and then 
the third, are longer than the others ; the tarsi are spinous. 
Plagusia, Latr 
Have their middle antennae lodged in two longitudinal and 
oblique fissures, traversing the entire thickness of the middle 
of the hood. V. depressa , Latr. 
They are inferior, or covered by this part in 
Grapsus, Lam . 
Their testa is a little wider in front than behind, or at least 
not more narrow, while in plagusia it widens a little from front 
to rear. Grapsus varius , Latr. 
Our fourth section, Orbiculat a, has the testa either sub- 
