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CLASS CRUSTACEA. 
ing macroura, four pair of false feet; and the middle antennae 
elbowed, and with two threads representing the stem, are 
manifestly shorter than their peduncle. That of the lateral 
antenna is never accompanied with a plate in the form of a 
scale. The two anterior feet only terminate in a didactylous 
hand, which is often extremely flatted. The last segment of 
the tail is bilobate, at least in the majority. 
At the head of this division will come those whose two 
posterior feet are much more slender than the preceding, fili- 
form, folded, and useless for running. 
Galathea, Fab ., 
Have the tail extended, the thorax almost ovoid, or oblong, 
the middle antennse projecting, and the forceps elongated. 
The upper part of the body is usually very much incised or 
striated, spiny, and ciliate. ( Galathea rugosa , Fab.) 
Dr. Leach forms with the galathea gregaria of Fabricius, 
a proper genus under the name of Grimotea. The second 
articulation of the intermediate antenna is terminated in a 
knob, and the last three of the external jaw-feet are foliace- 
ous. 
The Mgl ea of the same is not distinguished from the pre- 
ceding and from galathea, but by having the mandibles den- 
ticulated, the second articulation of the external jaw-feet 
shorter than the first, and the upper part of the body gene- 
rally even. 
Porcellana, Lam ., 
Form in the macroura, with reference to the tail, a very sin- 
gular exception ; it is folded underneath as in the brachyura. 
They are otherwise remote from galathea, in the more short- 
ened, suborbicular, or almost squared form of the thorax ; in 
having the middle antenna3 withdrawn within their fossets ; 
in their forceps being triangular ; and finally, by reason of 
