Botany and Zoology. 141 
the base of the antennae, a structure so essentially differing from that 
found in ordinary Brachyura. Dried specimens are too commonly used 
in these investigations, and are very apt to lead to error. The “ oper- 
eulum,” spoken of above, is the coxal joint (coxocerite) of the external 
antenne, which is moveable in all crabs, even where the next (basicerite) 
isnot. Ina Maia for example, this coxal joint may be raised a little, 
ic 
and articulated directly with the “ operculum’ same manner as it 
with the coxal joint in the other two genera named. Pilumnus, we 
May remark incidentally, would be classed with Parthenope by the char- 
acter of its antennse : 
pr 
ses new names for the first two joints of the external 
; bien “ee 
? 
th “ards, who has done so much towards elucidating the homologies of 
Se Joints, has given to them the names in brackets, which are more 
ne, and that the antenna in uestion, like a foot or maxilliped, con- 
Kren mally of seven joints. In the embryo of Hippolyte as figured 
er (Monog. Fremst, af Hippolyte’s Nordiske Arter, etc., tab. vi, 
. 
is 
1 
ever He So-called tympanum, It is very doubtful whether the au itory 
‘ver here sit d co ‘has ecesenied (Kong!. Danske Vide, 
complicated au 
; uated, ra he gare a 
wrifter, 1856, iv, 288) that a far more ditory apparatus exists at th 
