STOMAPODA. 423 



penda;re at the base, the fourth pair beinff the long-est. I only know one species {M. Lesueurii), collected in the 

 seas of North America. Olivier found, in the Penna marina, a crustaceous animal very similar at the first 

 sight ; but the specimens were so much injured tliat 1 was not able to study its characters. 



The Nehalice, which I had at first placed in this section, not having any natatory appendages under 

 the terminal segments of the body, and their legs being very similar to those of Cyclops, I have intro- 

 duced, together with Cmidylura, at the head of the order Branchiopoda. Nebalia, in its exposed eyes, 

 which appear to be pedunculated, and in some other chai-acters, seems, in conjunction with Zoea, to 

 unite the Scliizoj)oda with the Branchiopoda. 



THE SECOND ORDER OF CRUSTACEA,— 



STOMAPODA (commonly called Sea-]\Iantes), - 



Have the brauchia; naked, and adhering to the five pairs of appendages attached beneath the 

 abdomen or tail, which this part of the body also presents to us in the Decapods, which 

 appendages here, as in the majority of the Macroura, are used in swimming, or are iin-feet. 

 The carapax is divided into two parts, of which the anterior bears the eyes and intermediate 

 antennae, or more projierly composes the head without supporting the foot-jaws. The latter 

 organs, as well as the four fore-legs, often closely approach the mouth in two lines, converging 

 inferiorly : whence arises the name Stomapoda, given to this order. 



The heart — to judge at least from the SquillcB, the most remarkable genus in the order, 

 and the only one in which it has been studied — is elongated, and resembles a large vessel ex- 

 tending the whole length of the back, and terminating posteriorly near the anus, in a point. 

 The teguments of the Stomapoda are slender ; and, in some species, almost membranous 

 and dia])hanous. The carapax, or shell, is sometimes formed of two shields, of which the 

 anterior represents the head, and the other the thorax, sometimes of a single piece, but free 

 behind, leaving generally uncovered the thoracic segments, which bear the three hind pairs of 

 legs, and having in front an articulation serving as a base for the eyes and intermediate an- 

 tennae : the latter organs are alw'ays terminated by two or three filaments. The eyes are 

 always close together. The composition of the mouth is essentially the same as in the 

 Decapods ; but the palpi of the mandibles, instead of being adpressed to them, are always 

 raised. The foot-jaws are not furnished with the whip-like appendage [fouet) which exists in 

 the Decapods. They have the form of claw-legs, or small feet; and, in many at least {Squilla), 

 the base externally exliibits, as well as that of the two fore-legs, properly so called, a vesicular 

 body. The second pair of foot-jaws, in the same Stomapods, is much larger than the others, 

 and even than the legs themselves : hence they have been generally considered legs, and the 

 number of these organs has been stated to be fourteen.* The four anterior [true] legs have 

 also the form of claw-feet ; but are terminated, like the foot-jaws, by a hook which folds 

 upon the inferior and anterior edge of the preceding joint. But in some others, such as the 

 PhijUosomcef, all these organs are filiform, and without any didactyle claw. Some of these, 

 however, as well as the six hind-legs of the SquillcB, are furnished with a lateral appendage or 

 branch. The seven terminal segments of the body — inclosing a considerable portion of the 

 heart, and to which the respiratory organs are attached — cannot, moreover, in this respect, 

 be considered analogous {assimiles) to that portion of the body which is called the tail in the 

 Decapods, bcmg an abdomen, properly so called. Its penultimate segment has, on each side, 

 a swimmeret formed in the same manner as that of the tail of the Macroura, but often armed, 

 as well as the terminal segment or intermediate ])iece, with spines or teeth. 



All the Stomapoda are marine, preferring tropical climates, and not going beyond the tcni- 



* The second pair of true maxilla; n( the Siiiil/ic has not the saiiic I cate, and very much notched, 

 form as in the Decapods, being of an elonRated, Iriannular form, di- | t '» a" those which have the four anterior feet clan-like, the sii 

 Tided into four joints by trunavcrse iines. The mandibles are bifur- ' posterior arc formed for swimming. 



