176 
CRUSTACEA. 
The most common species — Cancer ruricola, L., Herbst,, III, 
36, when young, IV, xx, 116; xlix, 1, is of a more or less lively 
blood-red colour, more or less extended, and sometimes spotted 
with yellow with a deeply marked impression of the letter H. 
It is the Crahe violet, and Crabe peint of travellers ; the name 
of Tour lour ou appears to me to be more peculiarly applied to this 
species 
Sometimes the shell is nearly square, subisometrical or not, broader 
than it is long, flattened, and the front turned down for nearly the 
whole of its width. The ocular pedicles ai’e short and inserted at the 
anterior latei’al angles. The two ordinary divisions of the interme- 
diate antennae are very distinct. The inner sides of the exterior foot- 
jaws are separated, leaving an angular space between them ; their 
third joint is almost as long as it is broad. The claws are short and 
thick, and the other feet very flat; the fourth pair, and then the third, 
are longer than the others ; tarsi spinous. 
Plagusia, Lat. 
The mediate anteneae lodged in two longitudinal and oblique fissures 
traversing the whole thickness of the middle of the clypeus |. They 
are inferior or covered by this part in 
Grapsus, Lam. 
Where the shell is somewhat wider before than behind, or at least 
not narrower, while in the Plagusiae it widens from before back- 
wards. 
The Grapsi are found throughout all parts of the globe, but are 
more particularly abundant in the vicinity of the tropics. They are 
not seen in Europe beyond 50 deg. of latitude. If I mistake not they 
are called Ceriques at Martinique. Marcgrave has figured some 
Brazilian species by the name of Aratu, Aratu-pinima ( Grapsus 
cruentatus, Lat.) and Carava-una. At Cayenne they are called 
Ragabeumba, or soldier. 
These animals conceal themselves during the day under stones, 
&c., at the bottom of the sea. I have been informed that some of them 
even climb up the trees on its shores and hide beneath their bark. 
The broad and flattened form of their body and feet enables them to 
support themselves for a moment on the surface of the water ; they 
always walk sideways, sometimes to the right, and at others to the 
left. Certain species inhabit rivers within the bounds of tide water. 
* See the artiele Tourlouroic in the Encyc. Methodique. Messrs. Audouin and 
Edwards have lately communicated to the Acad. Roy. des Sc., some very curious 
remarks upon an organ peculiar to these animals, which form a sort of reservoir 
capable of containing a certain quantity of w'ater, and placed immediately above 
the branchiae. This accounts for the unusual convexity of the anterior sides of their 
thorax. 
-t P. depressa, Lat. ; Herbst., Ill, .15 ; — P. clavimana, Lat., Herbst., lix, 3 ; 
Desmar., Consider., XIV, 2. The tail appears to me to consist but of four distinct 
segments. The third, however, presents one or two deep and transverse lines. In 
the Grapsi there are seven segments, the third of which has an angular dilatation on 
each side of its base. 
