MONOCITT.US. 
496 
ill front, and lunated behind, where it joins the 
lower part of the body: this, which is of the same 
crustaceous nature, is marked on each side into 
several spiny incisions: the legs which are seven 
on each side, are situated beneath the concavity 
of the large or rounded part of the shell, and are 
each terminated bv a double claw, those of the 
lowest pair having some additional processes : the 
branchias or respiratory organs are disposed in 
the form of several flat, rounded, imbricated la- 
mellag on each side the lower part of the body: 
the tail, which is strait, triangular, and of the 
same crustaceous nature with the rest of the shell, 
is equal in length to the whole body, and gradually 
tapers to a sharp point. The eyes in this species, 
instead of being approximated, as required in the 
Linnaean generic character, are extremely distant 
from each other, being situated towards the sides 
of the shell: they are of a semilunar form, and the 
surface is divided into a great number of minute 
conical convexities: this part however should be 
considered only as constituting the cornea or ex- 
terior covering of each eye ; the organs them- 
selves being, according to the observations of Air. 
Petiver, in the Philosophical Transactions, placed 
on a pedicle beneath each of the above-mentioned 
semilunar cornem. Petiver’s words are these. “The 
whole structure of this animal is very remarkable, 
and jiarticularly his eyes, viz. between the I’ourth 
and last pair of claws on each side, reckoning 
from his mouth, and excluding the small pair there 
placed, are inserted the rudiments of another pair. 
