ATOM A POD A. 211 



the lateral part of the abdomen, reach the anterior margin of the pre- 

 ceding ring, arid terminate on the superior surface of the heart near 

 the median lino, one partly mounting on the other. The medullary 

 cord, exclusive of the brain, presents but ten ganglions, of which the 

 anterior furnishes nerves to the mouth the three following, those 

 of the six natatory feet, and the last six, those of the tail. Thus, 

 although the four last foot-jaws represent the four anterior feet 

 of the Decapods, they nevertheless form a part of the organs of man- 

 ducation. The stomach of these Crustacea Squillae is small and 

 has but a few very small teeth* near the pylorus. It is followed by a 

 Mi-iiitrht and slender intestine which extends along the whole abdo- 

 men, accompanied on the right and left by glandular lobes, which 

 appear to supply the want of a liver. A ramous appendage adhering 

 to the inner base of the last pair of feet appears to characterize the 

 male. 



The teguments of the Stomapoda are thin, and, in several, nearly 

 membranous or diaphanous. The shell is sometimes formed of two 

 shields, of which the anterior corresponds to the head, and the pos- 

 terior to the thorax, and sometimes of a single piece, which however 

 is free behind, usually exposing the thoracic segments, bearing the 

 three last pairs of feet, and having an articulation before that serves 

 as a base to the eyes and intermediate antennae ; these latter organs 

 are always extended and terminated by two or three threads. The 

 eyes are always approximated. The formation of the mouth is 

 essentially the same as in the Decapoda ; but the palpi of the mandi- 

 bles, instead of being laid on them, are always vertical. The foot- 

 jaws are deprived of the flagelliform appendage presented to us by the 

 same parts in the Decapoda. They have the form of claws, or of 

 small feet, and, at least in several the Squillse, their external base 

 as well as that of the two anterior feet properly so called, exhibits a 

 v >icular body. Those of the second pair, in the same Stomapoda, are 

 much larger than the others, and even than the feet, which has caused 

 thorn to be considered as true feet; fourteen of them have been 

 counted f. The four anterior feet have also the form of claws, but 

 are terminated as well as the foot-jaws by a hook which curves to- 

 wards the head, on the inferior and anterior edge of the preceding 

 joint or of the hand. In others however the Phyllosoma for instance}; 



* They form two ranges of transverse and parallel striae. 



t The second jaws of these Stomapoda no longer present the same form as those 

 of the Decapoda. They have the figure of an elongated triangle divided into four 

 segments by transverse lines. The mandibles arc bifurcated and well dentated. 



J In all those where the four auterior feet are in the form of claws, the six last 

 are natatory. 



p 2 



