ORDER PCECILOPODA. 
365 
(Zool. Misc. lxxiv.) ; his Limulus tridentatus, and the Limule 
blcinc of M. Bose ; and to the second individuals, or the largest, 
my Limule des Moluqu.es ( Monoculus polyphemus, Lin. ; 
Crus. Exot.,liv. 6. cap. 14. p. 128; Rumph. mus. xii. a, b.) 
which I had at first distinguished specifically, in the belief 
that these large individuals exclusively inhabited those islands. 
In both, that is, at all ages, the tail is a little shorter than the 
body, triangular, finely denticulated at the upper crest, with- 
out any defined furrow underneath. We shall designate this 
species under the name of limulus polyphemus. These last 
characters will distinguish it from some others described by 
me and Dr. Leach. (See the second edition of the Nouveau 
Diet. dTIist. Nat. Desmarets. Consid. p. 344 — 358.) 
The second family, that of 
SlPHONOSTOMA, 
Presents no kind of jaws whatsoever. A sucker or siphon, 
sometimes external, and in the form of a sharp inarticulated 
beak, sometimes concealed or scarcely distinct, replaces the 
mouth ; the number of the feet is never beyond fourteen ; the 
testa is very slender, and consisting of a single piece. These 
entomostraca are all parasitical. 
The composition of the beak is not yet well known. It is 
evident, from the figure given by the younger Jurine, of the 
ary ulus foliaceus, that it encloses a sucker. But is this the 
case with that of the others, and what is the number of its 
pieces ? On these points we are ignorant. I presume, how- 
ever, that this siphon is composed of the labrum, the mandi- 
bles, and the ligula, which forms the sheath of the sucker. 
In the preceding entomostracon, the four anterior feet, the 
form of which is very different from that of the following, would 
correspond to the four jaws of the decapods. 
We shall divide this family into two tribes. 
The first, that of Caligides, Lat., is characterized by the 
