DECAPODA. 203 



Their body is arcuated, almost gibbous, and of a less solid con- 

 sistence than that of the preceding Crustacea. The front is always 

 drawn out into a point, and most frequently so as to resemble a ros- 

 trum or pointed lamina compressed and dentated along the edges. 

 The antennae always project ; the laterals are usually very long and 

 resemble very fine setae; the intermediaries of a great number ter- 

 minate in three threads. The eyes are closely approximated. The 

 external foot-jaws, more elongated and narrow than usual, resemble 

 palpi or attennse. The mandibles of most of tlicm are compressed 

 and arcuated at the extremity. One of the first pairs of feet is fre- 

 quently flexed upon itself. The segments of the tail are dilated or 

 widened laterally. The external leaflet of its terminal fin is always 

 divided in two by a suture, a character observed nowhere else ex- 

 cept in the last Crustacea of the preceding section ; the azygous por- 

 tion of the middle, or the seventh and last segment, is elongated, 

 narrowed near the extremity, and ]n-ovided above with ranges of 

 small spines. The false feet, of which there are five pairs, are elon- 

 gated and usually foliaccous. 



Immense numbers of these Crustacea are consumed in all parts 

 of the world. Some species are even salted in order to preserve 

 them. 



In some of them, the three first pairs of feet form a didactyle claw, 

 the length of which progressively augments, so that the third pair is 

 the longest. Such are the 



Pen.^us, Fab., 



Where there is no annular division in any" of tlie joints of the 

 feet. 



Their mandibular palpi are turned up and foliaceous. A little 

 elliptical api^endage may be seen at the base of the feet, a character 

 which seems to approximate them to Pasipheea, the last genus of this 

 section, and to those of the following one. 



Some, all indigenous to Europe, on account of the shortness of the 

 two threads of their intermediate antennae, form a first division. It 

 contains the following sjjecies. 



P. sulcatus ; Palcemon sulcatus, Oliv., Encyclop. ; Caramote, 

 Rond., Hist. Nat. des PoisB., liv. xviii, chap. 7- Nine inches 

 long ; on the middle of the thorax a longitudinal carina bifur- 

 cated at base, terminated by a projecting rostrum, compressed, 

 witli eleven teeth in its upper edge and one in the lower ; a lon- 

 gitudinal sulcus along each side of the carina. 



This species is very common in the Mediterranean and the 

 object of considerable commerce. It is salted and shipped to 

 the Levant. The P. trisulcatus. Leach, Malac. Brit. XLII, 

 which inhabits the coast of England, is perhaps a mere local 

 variety of the sulcatus. Its thorax is trisulcate and the rostnmi 

 bidentate beneath. In the P. d'Orhigny, — Lat., Nouv. Diet. 

 d'Hist, Nat., Ed. II, article Pence, the carina is not sulcated. 



The intermediate antennae of others are terminated by long 

 threads ; they constitute our second division, to which we refer. 



