ORDER DECAPO DA. 
193 
Hippolyte, Leach , 
Are removed from Alpheus only by the respective proportions 
of the claws ; the second are longer than the first. ( Palcemon 
diver simana , Oliv.) 
The last two subgenera following, have this peculiarity, 
that one pair only of their feet is terminated in a didactylous 
forceps. In 
Antonomea, Risso, 
It is the two anterior, which are distinguished from the 
others, by their size, thickness, and disproportion. (. Antonomea 
Oliviiy Risso.) 
Pandalus, Leach. 
The two anterior feet are simple, or scarcely bifid ; the two 
following are longer, of an unequal length, didactylous, with 
the carpus and the preceding articulation annulated. 
The external jaw-feet are slender and very long, at least in 
some; the anterior projection of the testa is very long and 
much denticulated. ( Pandalus annulicornis , Leach.) 
Sometimes the upper antennae have three threads ; these 
Crustacea have four didactylous claws, the smallest of which 
are folded and the bill elongated. 
PaLjEMON, Fab., 
Are distinguished from the two following subgenera, by their 
inarticulated carpus ; the second feet are larger than the first ; 
these last are folded. (P. serratus , Leach.) 
The carpus is articulated, or presents some annular divi- 
sions in the two following subgenera : 
Lysmata, Risso , 
Which have the second pair of claws larger than the first. 
(- Lysmata seticauda , Risso.) 
YOL. XII I. O 
