BECAPODA. 421 



is always prolonged into a point, often forming a sliaTp-pointecl plate, very much compressed, and 

 tootlied oil botli erlgcs. The antennae are always advanced; the lateral ones generally very long, and 

 in tlie form of a very slender thread: the intermediate antennae, in the majority, are terminated hy 

 tlirce filaments. The eyes closely approach each other. The outer foot-jaws, longer than ordinaiy, 

 resemlilc ]ial]ji or antcnna\ One of tliu two foi'c pair of legs ii often folded back, or doubled. Tlie seg- 

 ments of tin; tail arc diluted laterally. The outer plate of the terminal swimmeret is always divided in 

 two by a suture, as in tlic terminal species of the preceding section. The middle piece, or the seventh 

 and la>,t segment of the tail, is long, narrowed towards tbe tip, and is armed aljove with rows of small 

 sjiiiies. The false legs, of "which there are five pairs, are long andfoliaeeous. Tliese Crustacea are much 

 eaten in ditferent parts of the world, and some species are salted for keeping.* 



Those v.'hicli liave the three anterior pairs of legs didactyle, the length p:radnally increasing, so that the tliird 

 pair is the largest, compose the genera Penifus, Fahr., (having no annular divisions in tlie joints of the Ie£:s, arjd 

 composed of numerous species, one of which, the Caramote {P. sulcatus, OUv.), is very common in the Mediter- 

 ranean, and is a great ohject of commerce, beinj? snlted for exportation to the Levant, and of which the Engiish 

 spccief^ (/-'. irisidcatu.s. Leach) is considered by Latreille to be a local variety), — and Stenopus, Fabr., havinf>; the two 

 penultimate joints of the four posterior legs with annular divisions. 



The roMiaioinfr species have not more than the two anterior puirs of Vy;^s dulactyle, and the intermediate antennae 

 terminated by three tilaraents. 



Ati/a, Leach, formed of a single North American species, A. scabra, is anomalous in the form of its four claws, 

 which are small, and split to the base with long terminal pencils of hair, the preceding' joint beinjj crescent-shaped. 



The others have the claws of the ordinary didactyle form. Tliese, with the exception of the terminal genus, have 

 the legs more or less robust, but not filiform, without any appendage at the base. The body is neither very soft, 

 nor very much elongated. 



Crangon, Fabr., has the fixed finger or index of the two anterior and largest claws rpduce<l to a small tooth, tlie 

 moveable finger being hook-shaped. The superior or intermediate antcnnjt have only two terminal filaments ; the 

 second legs are folded, and more or less distinctly didactyle at the tips ; none of the joints are annulated ; the 

 rostrum is very short. Crangon vulgaris, Fabr., the Common Shrimp, i:^ the type of this genus. It does not 

 exceed two inches in length, and is of a pale glaucous green colour, dotted with grey. It is caught tlnuughout 

 the year with the assistance of circular nets. Its tlesh is delicate. 



Pontophilus, Leach {Egeon, Risso), does not geuerically differ from Crangon. 



Processa, Leach (iV(Art, Risso), has one of the fore-legs terminated in a point, and the other didactyle. The 

 second pair of legs are of unequal length, one being vei-y long, with the two joints preceding the claw annulated. 

 N. edulis, Risso, found at the mouth of the Rhone. 



Hlimenocera, Latr., differs in the proportions and form of the legs. 



To these succeed a number of genera in which the legs and claws do not present any anomalous structure, and 

 in which the superior or intermediate antenna have only two terminal filaments, inchiding the genus liijipohjte. 

 Leach, comprising several Rritish species of shrimps, and in which the four fore-legs 

 are terminated by a didactyle claw, the second pair being longer than the first ; and 

 Painlalus, Leach, comprising another British species {P. ai/mrleconns, Leach), in 

 which the fore-legs are [very small and] simple, or scarcely bifid; the two following 

 long, of unequal length, with the two joints preceding the claw annulated. 

 The Prawn is the type of the genus Palu-mon, which difiers from the last group 

 '^'' '' " ■ ' ■ ^c jvgj^igj-a^ jji having the upper antennas terminated by three filaments. It has 



the two anterior pairs of legs didactyle, the smaller pair being folded; and the carpus is not articulated. The 

 rostrum is very long [and spincd]. Some of the exotic species acquire a very large size, with the second pair of 

 1( gs very long. The flesh of the common species is more esteemed than that of the Shrimp. According to M. 

 de Brebisson {Cat. Mclh. Crust. Depart, da Calvados), they are caught in the same manner as Shrimps, but only 

 ill summer. They swim well, especially when alarmed, and in different directions. They frequent the coast. The 

 lithographic stone of Pappenheim and Sohlnofen often contains the remains of a fossil species, which Desmarest 

 names Paltemon spinipes. Another fossil species, but of a much larger size, has been found in England. The 

 species ordinarily sold in the fish-shops is the Palccmon serra/ir.s: It is generally three or four inches long, and of 

 a pale red colour, which is brightest in the antennse, and especially in the swnnmcret of the tail. Its frontal spine 

 extends beyond the peduncle of the middle antennae : it is curved upwards at the tip, with seven or eight spines 

 above, and five beneath. One of the sidc^s of the body is often distended, which is caused by a parasite of the 

 genus liopi/nis beneath the carapax, affixed to the branchiye. PaUcmon xqnilla, Linn., is another but smaller 



* [The irriiflufil devclnpemeiit of scvural species of Carides (P^ila?- and ridi.e tif tlie e;ir:ipa\ .spirieJ ; ihe five jmirs of Je^s extended to 



niniiidtc) Ikis been recently described by I>r. J.V. Thompson in Jnine- tlieir full sizi-, l>ut still biiid ; and the sububdotiiiiiTil appendii^es and 



son's Edhib. Pliil. Joiiru., Oet. laiG, and by Captnin Ducane in the the swimmeret^ (gradually developed. These observations are as- 



/f/««/j <'/iV'/(. ///s'., Ni>v. 133S. On first bursting from the cgjj, tbe berled, by M'Leay and others, tu afford a complete confiriuation of 



iiil is terminated by a spatulated plate, destitute of lateral as -well as the correctness of Thonivsoii's assertions that Zoea is the larva of the 



Mihabdoniinal appendages ; the rostrum is produced into a simple common Crab, and that all the Crustacea underijo trani-forniations,— 



T,.iiiitj the lateral anteiiiitc exhibit only tbe large scale ; and oidy t-.vo tbese Kentlenicn overlooking ibe fact tliat Zoea is a Uecapml animal, 



1-1 llie legs are of the ordinary lerig-th, ami these are bifid, as In the . not furnished willi biiid Ie^^•^, but having llie two pairs iif nnter foot- 



Si.hii.rpnds ; tlie other leirs are very minute, and incurved. In the jaws immensely developed, but of ihe onlinary Mueruuruna eons.ruc- 



o,ur=c of se"vor:il muuliin.i;^, tl;e antennae are leii-t!.'':ied ; the rostrum | tion, as are the internal pi.-ti ol Us muiilh.] 



