2i2 CRUSTACEA. 



— all these organs are filiform and have no forceps. Some of them at 

 least, as well as the last six and eqvially simple ones of the Stomapoda 

 provided with claws, have an appendage or lateral branch. The 

 seven last segments of the body, containing a large portion of the 

 heart and furnishing a base for the attachment of the respiratory or- 

 gans, can no longer in this respect be assimilated to that portion of the 

 body which is called the tail in the Decapoda : it is a true abdomen. 

 Its penultimate segment has a fin on each side formed like the caudal 

 of the Macroura, but is frequently, as well as tlie last segment or 

 intermediate portion, armed with spines or teetli. 



The Stomapoda are all marine Crustacea. Their favourite habita- 

 tion is in the intertropical latitudes, and they are not fo\md beyond the 

 temperate zones. Of their habits we are totally ignorant ; that those 

 which are furnished with claws use them in seizing their prey, in the 

 manner of those Orthoptera called in Provence Pregadious or 3fan- 

 tes*, wc cannot doubt. Hence their vulgar appellation of Sea- 

 Mantis: they are the Crangones and Crangines of the Greeks. 

 According to Risso they prefer sandy bottoms in deep water, and 

 copulate in the spring. Other Stomapoda, those of our second family, 

 being less favoured witli natatory appendages, and having a much 

 flatter and more superficially extended body, are generally found on 

 the surface of the water, where they move very slowly. We will 

 divide the Stomapoda into two families. 



FAMILY T. 



UNIPELTATA. 



In this family the sliell consists of a single shield, of an elongated 

 quadrilateral form, usually widened and free behind, covering the 

 head, the antennae and eyes excepted, which are placed on a common 

 anterior articulation, and at least the first segments of the body. Its 

 anterior extremity terminates in a point, or is preceded by a small 

 plate with a similar end. All the foot-jaws, the second of which are 

 very large, and the four anterior feet are closely approximated to the 

 mouth on two inferiorly converging lines, and have the form of 

 claws with a single finger or mobile and flexed hook. With the 

 exception of the second feet, all these organs are furnished at their 

 external origin with a little pediculated vesicle. The other six feet, 

 at the base of whose third segment is a lateral appendage, are linear, 

 terminated by a brush, and simply natatory. The lateral antennae 



* Some other analogous Orthoptera, such as the PhijlUum, resemble leaves. The 

 Phyllosomse, Crustacea of the same order, exhibit similar affinities. 



