198 
CRUSTACEA. 
foot-jaws are foliaceous. It is of a red colour, and was discovered by 
Sir Joseph Banks in liis voyage round the world. It collected in 
such immense numbers that the Ocean seemed to be of one blood-red 
colour. 
The JEqlea^ Id., is only distinguished from the ])receding genus, 
and from Galathea, by the dentation of the mandibles, by the second 
joint of the external foot-jaws being shorter than the first, and by the 
surface of the body being generally smooth *. 
That which Risso first named Calypso, and subsequently Janira, 
in the opinion of Desmarest, — Consider., p. 192, does not differ from 
Galathea. 
PoRCELLANA, Lam. 
The Porcellanae form a singular exception among the Macroura, 
with respect to their tail, which is doubled under as in the Brachyura. 
They are otherwise removed from the Galathese by the more ab- 
breviated, suborbicular, or almost square form of their thorax ; by 
the mediate antennae, which are sunk in their fossulae, by their tri- 
angular forceps ; and finally, by the internal dilatation of the inferior 
joints of their external foot-jaws. Their body is very flat. 
They are small, slowly-moving Crustacea, found in every sea, 
and conceal themselves under stones near the shore. 
Doctor Leach has formed a genus Avith certain species — hexapus 
Latr., — longiconiis. Id., — Bluteli, Risso, Crust., I, 7? &c., Avhich he 
calls PisiDiA. According to Desmarest, however, it does not differ 
in any appreciable character. 
Some of them are remarkable for their extremely large and pilose 
or ciliated forceps. Such are, 1. The Porcellane larges pinces ; Can- 
cer platycheles, Penn., Brit. Zook, IV, vi, 12; Herbst., XLVII, 2, 
Avhere only the external margin of the forceps is pilose and the nearly 
naked thorax is rounded; it is found on the rocks in the seas of 
Europe. 2. The P. Itirta, Lam., the Avhole superior surface of 
whose forceps and thorax is pilose, and where the latter is nearly 
oval and becomes thinner anteriorly. It was brought from King’s 
Island by Messrs, Peron and Lesueur. 
The forceps of the others are glabrous. Such is the Cancer hex- 
apus, L. ; Herbst. XLVII, 4. The thorax is marked with short, 
transverse, and slightly ciliated lines : the front trifid, Avith its middle 
tooth finally notched. The cHaa’s are covered Avith little blood-red 
scales and granules, the fingers sejiarated and Avithout internal den- 
tations. It inhabits European seas f . 
The genus Monolepis , Say, — Journ. of the Acad, of Nat. Sc. of 
Philad., I, 155; Desmar., Consid., p. 199 and 200, appears to con- 
stitute the passage from the Porcellanae to the Megalopes. It ap- 
proaches the first in the tAvo jiostcrior feet, and in the direction of the 
tail. But this tail has but six segments, and the eyes are A'^ery large 
* j^cjUe lisse, Desmar., Consider., xxxiii, 2 ; Latr., Encyclop. Method., Atl., 
d’llist. Nat. cccviii, 2. 
t See the article Porcellane, Nouv. Diet. d’Hist. Nat., Ed., II. ; and Desmar., 
Consid. sur les Crust., p. 192 — 199. 
