424 



CRUSTACEA. 



perate zones. Although we have observed a very great number of individuals, we have never 

 met with one carrying eggs. Their habits are entirely unknown. It is, however, beyond a 

 doubt, that those species with powerful claws use them for the purpose of seizing their prey 

 in the same manner as those Orthoptera which are named Mantes * ; and it is on account of 

 this conformity that these Stomapods have received the name of Sea-Mantes. They were 

 named Crangones, or Crangines, by the Greeks. 



According to M. Risso, they keep in deep water, in sandy and muddy bottoms, and couple 

 in the spring; but other species, forming our second family, being less favoured in respect to 

 their natatory appendages, and having the body very flat and extended in its surface, are 

 ordinarily found on the surface of the ocean, where they move but slowly. 



We divide the order Stomapoda into two families. In 



THE FIRST FAMILY OF STOMAPODA,— 

 Unipeltata, — 



The carapax forms only a single shield of a quadrilateral, elongated shape, generally widened and free 

 behind, covering the head (with the exception of the eyes and antennae, which are implanted upon 

 common and frontal articulations), and at least the anterior segments of the thorax. Its anterior ex- 

 tremity terminates in a point, and is preceded by a small plate terminating in the same manner. All 

 the foot-jaws (of which the second pair is very large), and the four anterior feet, are inserted close to 

 the mouth in two lines converging inferiorly, in the form of claw-feet, with a single moveable and 

 folded back finger. With the exception of the second pair of legs, all these organs are externally fur- 

 nished at the base with a small pedunculated vescicle. The other feet, six in number, are linear, ter- 

 minated by a brush, and merely natatorial : the third joint is furnished at the side and base with a 

 slender appendage. The lateral antennae have a scale at the base, and the intermediate are terminated 

 by three filaments. The body is narrow and elongated. The ocular peduncles are always short. This 

 family comprises the single genus 



Sciuilla (Fabr.), — 

 which we divide as follows : — 



In some species, the crustaceous shield [or carapax] is preceded by a small, more or less triangular, plate, situ- 

 ated above the articulation which bears the intermediate antennae and the eyes. It does not cover the anterior 

 portion of the thorax, and is not bent down at the sides. The joint which serves as a footstalk to the peduncle of 

 the intermediate antennae, as well as to the ocular peduncles and the exterior margins of the extremity of the 

 abdomen, is exposed. 

 Squilla proper, Latr., has the entire inner edge of the penultimate joint of the two great claw-feet furnished 



with a narrow channel, denticulated on one 

 side, and spined on the other ; and the follow- 

 ing joint is sickle-shaped, and often toothed. 

 The type {Cancer mantis, Linn.) is about seven 

 inches long. Its great claws have at the base 

 three moveable spines; and the terminal 

 joint has six long and very sharp spines, of 

 which the terminal is the strongest. The seg- 

 ments of the body, except the last, have six 

 longitudinal elevated lines, ordinarily termi- 

 nating in an acute point. It is common in 

 the Mediterranean. 



Fig. 9.— Squilla Mantis. 



Gonodaetylus, Latr., has the channel of the great claws unarmed with points ; and the terminal joint is dilated 

 into a knob at its base. The species are exotic. (Squilla chiragra, Fabr. ; Desmarest, pi. 43.) 



Coronis, Latr., has the body very narrow and depressed, with the terminal segment square and entire, without 

 teeth or spines. The lateral appendage of the six hind-legs is pallet-shaped. [C. scolopendra, Latr., regarded by 

 Uim as synonymous with Squilla Eusebia of Risso ; but the figure given by this author in his Hist. Nat. Ew op. 

 Mend., torn. v. pi. 4, has the terminal segment deeply toothed.] 



In the other species of this family, the carapax is slender, nearly membranous, diaphanous, entirely covering 

 the thorax, bent down at the sides, prolonged in front into an acute spine, and advanced over the stem of the in- 

 termediate antennas, and the eyes. This stem is capable of being bent downwards, and inclosed in the shield 

 formed by the curve of the carapax. The posterior swimmerets are hidden beneath the terminal segment. 



* Some other analogous Orthoptera (such as th» genus Phyllium) resemble leaves. The Phyllosomae, Crustacea of tho same order, ex- 

 hibit .j us the same analogy. 



