ORDER PCECILOPODA . 365 



(Zool. Misc. Ixxiv.) ; his Limulus tridentatus, and the Limule 

 hlanc of M. Bosc ; and to the second individuals, or the largest, 

 my Limule des Molnques f Monocidus polyphetmis, Lin. ; 

 Cms. Exot.jliv. 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 limidus polyphemus. These last 

 characters will distinguish it from some others described by 

 me and Dr. Leach. {See the second edition of the Nouveau 

 Diet. d'Hist. Nat. Desmarets. Consid. p. 344—358.) 

 The second family, that of 



SiPHONOSTOMA, 



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 

 argidus foUaceus, 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 

 coiTespond 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 



