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THE CORYSTES.— CASSIVELAUNUS. 



rnay belong. The embryo Cray-lisli (Palinuriis) was 

 considered by the earlier naturalists a distinct genus, 

 and named Phyllosoma, or Glass-crab. The [lopnlar 

 name refers to the transparency of their bodies; the 

 Ecientific to the remarkable horizontal expansion of the 

 carapace. In the members of this genus the head is 

 represented by a large oval plate, bearing eyes mounted 

 on very long stalks; the thorax by a second plate, much 

 broader than it is long, carrying the feet, most of which 

 are long and some bifid, with one branch exceeding 

 the other in length. Milne-Edwards described them 

 as deficient in special respiratory apparatus, but having 

 the blood aerated through the general superficies of 

 the body. 



It is now understood, however, that the so-called 

 Phyllosoma are, in reality, the young of the higher 

 forms of Crustacea, undergoing a process of meta- 

 Diorphosis. In the Macroura this metamorphosis is 

 less remarkable than in the Brachyura, while no change 

 at all is undergone by the fresh-water cray-fish. 



From experiments made by Mr. Couch, we find that 

 metamorphosis takes place in the following genera: — 



Cancer; Znntko; Peluvmus ; Cacernus; Portumnus; Main; 

 Gahithea ; Homarus ; and Palinurus. 



Metamorphosis has been demonstrated, adds Dr. 

 Bell, in no less than seventeen genera of the Brachy- 

 ourous order of Decapoda, in which it is most decided 

 and obvious; in the Leptopodiadw, Maiadoe, Canceridfe, 

 Porturanidas, Pinnotheridae, and GrapsidiE. In the 

 Anomourous order it occurs in the Pagurus, Porcellana, 

 and Galathea ; and in the Macrouran order in Homa- 

 rus, Palinurus, Palsemon, and Crangon. 



There exists almost as great a diversity in size and 

 species among Crabs as among the Mytilidte. Not 

 one of the least curious is the Long-clawed Crab 

 {Coiystes Cassivelaimus) of Peimaiit and Leach, whose 

 antenuje considerably exceed its body in length. In 

 the jaw-feet the third joint is longer than the second, 

 and terminates in an obtuse ]ioint, with a notch on its 

 interior edge. The eyes are set wide apart upon large 

 peduncles, which are short, and nearly cylindrical. The 

 anterior feet in the males are large, being twice the 

 length of the body, and nearly cylindrical ; in the 

 females they are flatter, and not longer than the body. 

 The other feet terminate in an elongated nail or claw, 

 ■which is straight-pointed, with a longitudinal groove 

 or furrow. The carapace is an oblong oval, ending in 

 a rostrum truncated in the fore and bordered in the 

 hinder parts ; the various regions are not very plainly 

 marked, with the exception of the cordian, the branchial 

 or lateral being very much elongated. 



This genus received the name of Corj-stes, or war- 

 rior-armed (xf/pu?, a helmet), from Latreille ; and it 

 had already been christened Cassivelaunus, by Pen- 

 nant, in allusion to the old Celtic warrior that so gal- 

 lantly withstood the invading Normans. According 

 to Gosse, Pennant was inspired to choose this name, 

 because the carapace bears, in old males especially, a 

 ludicrous resemblance in its numerous wrinkles to the 

 rugose countenance of a venerable elder. But Pen- 

 nant was too enthusiastic a Celt to have cast any 

 ridicule on the great British warrior. Seeing in the 



formidable Crustacean a creature armed cap-a-pii, ho 

 named it after the hero of his imagination. 



The surface of the carapace in this species is some- 

 what granulous, with two denticles between the eyes, 

 and three sharp points inclined forward on either side. 

 The male has only five abdominal pieces, but the ves- 

 tiges of the separation of the two others are conspicu- 

 ous on the outer mediate, or third piece, which is the 

 largest of all. 



Mr. Couch* remarks on the extraordinarily long 

 antenna;, tliat they are of service beyond and in addition 

 to their common ability as feelers; perhaps, as in some 

 other Crustacea, they assist in the process of exca- 

 vation ; and, when soiled by labour, I have seen the 

 crab effect .their cleansing by alternately bending the 

 joints of their stalks, which stand conveniently angular 

 for the purpose. Each of the long antennae is thus 

 drawn along the brush that fringes the internal face of 

 the other, until both are cleared of every particle that 

 adhered to them. 



Mr. Gosse, however, is of oiiinion that the function 

 of these antenna; is to keep open a passage for the 

 emission of the deteriorated water after it has bathed 

 and aerated the gills or branthiw. 



"I have observed," he says, " that, when kept in an 

 aquarium, these crabs are fond of sitting perfectly 

 upright, the antennse placed close together, and point- 

 ing straight upwards from the head. This, doubtless, 

 is the attitude in which the animal sits in its burrow, 

 for the tips of the antennae may often be seen just 

 projecting from the sand. 



" When the chosen seat has happened to be so close 

 to the glass side of the tank as to bring the antennre 

 within the range of a pocket lens, I have minutely 

 investigated these organs without disturbing the old 

 warrior in his meditation. I saw on each occasion 

 that a current of water was continuously pouring up 

 from the points of the antennje. Tracing this to its 

 origin, it became evident that it was produced by the 

 rapid vibration of the foot-jaws drawing in the sur- 

 rounding water, and pouring it off upwards between the 

 united antennae as through a tube. Then, on examin- 

 ing these organs, I perceived that the form and arrange- 

 ment of their bristles did indeed constitute each antennae 

 a semi-tube, so that when the pair was brought face 

 to face the tube was complete." 



It should be added that the Corystes, notwithstand- 

 ingits formidable appellation, is harmless and inoflensive 

 in its habits. 



Lobsters abound on the British coast; iidiabiling the 

 clearer water and rocky shores, and frequenting the 

 shallows near the shore about the time of depositing 

 their eggs. In Scotland they are collected and kept 

 in perforated chests, floating on the water, until they 

 can be transported to market. They are conveyed to 

 the Thames, the Cljde, or the Mersey, in welled fishing 

 smacks constructed specially for this purpose. But, 

 as M. Fredol points out, this antiquated system is 

 giving place to the greater conveniences afforded by 

 artificial storing ponds or reservoirs. Mr. Humble has 

 established one of these near Southampton, where ho 

 can accommodate with ease as many as fifty thousand 

 • Couch, Cornish Fanna^ 



