19G CLASS CRUSTACEA. 



THE SECOND ORDER OF CRUSTACEA. 



STOMAPODA 



Have their gills exposed, and adherent to the five pairs of ap- 

 pendages situated under the abdomen, (the tail) which this 

 part presented us in the decapods, and which here, as in the 

 majority of the macrouri, serve for swimming, or are fin feet. 

 Their testa is divided into two parts, the anterior of which 

 carries the eyes and the intermediate antennae, or forms the 

 head, without bearing the fin-feet. These organs, as well as 

 the four anterior feet, are often approximated to the mouth, 

 on two lines converging inferiorly, and from thence the deno- 

 mination of Stomapods given to this order. The heart, to 

 judge from the squilla^, the most remarkable genus of this 

 order, and the only one which has been studied, is elongated, 

 and similar to a thick vessel. It extends all along the back, 

 reposes on the liver and the intestinal canal, and terminates 

 posteriorly and near the anus in a point. Its parietes are 

 slender, transparent, and almost membranaceous. Its ante- 

 rior extremity, placed immediately behind the stomach, gives 

 birth to three principal arteries, the middle one of which (the 

 ophthamic) throwing out from both sides many branches, is 

 more especially carried to the eyes and the middle antennae, 

 and the two lateral (the antennary) pass over the sides of the 

 stomach, and lose themselves in the muscles of the mouth, 

 and of the external antennae. The superior surface of the 

 heart produces no artery, but a great number are seen to issue' 

 from its two sides ; and each pair, as it appears to us, corre- 

 sponds with each segment of the body, commencing at the 



