022 



It RAC II Y \J 11 A. 



The edible rritli and the lobster may be cited as the 

 two best known species belonging to the l)i-i-ufl 

 liibe of CritxIfitTtt ; but these two animals differ mate- 

 rially from each other in their structure. In the 

 former the body is broader than long, the abdomen 

 very nightly developed. incapable of being employed 

 in swimming, unflirnUbed beneath with lamcllated 

 fidse legs, iis they are termed, and not terminated by 

 an apparatus for swimming. In the latter the reverse 

 of all this taken plaee : the abdomen or tail of the 

 lobster, an every epicure can tell, is very much deve- 

 loped, generally longer than the body, which is nar- 

 rower than long, and furnished beneath wilh abort 

 natatory appendages, and terminated in a fan-shaped 

 wimming apparatus. Now these two animals form 

 the types of two of the chief divisions of the Cnutacea, 

 the former representing the order lirachyuri, or short- 

 tailed crabs, and the latter the order Macrura, or 

 long-tailed lobsters. These two orders or divisions, 

 in the arrangements of the majority of authors, com- 

 prise all the decapod Cnutacea ; but M. Milne 

 Edwards, one of the most celebrated of modern 

 erustaccologists, in a valuable work published at Paris, 

 in IH.'IJ, has proposed the establishment of another 

 or i Inn! division, under the name of Anomourrs, form- 

 ing a passage between the two other groups, and 

 composed of various species which appear to belong 

 to neither, and which, if introduced amongst them, 

 would violate the spirit of all natural arrangement. 



In the various animals which compose the division 

 lirar/iyura, the shell or carapace which covers their 

 bodies, also conceals the greatest portion of the abdo- 

 men, and is in general of a square oval or rounded 

 form, its transverse diameter exceeding, or at least 

 equalling its length, its upper surface exhibiting 

 various areas divided by impressions which corre- 

 spond for the most part with the insertion of the 



Curclnus Mronns. 



, muscles wituin the shell, and which form so many 

 regions corresponding with the internal organs imme- 

 diately beneath the different ureas. The front of this 

 shell bears u pair of eyes placed on footstalks, and 

 two pairs of antenna-, and beneath these is perceived 

 u puir of large, Hat, and articulated pieces, which 

 when raised, are found to conceal a very complex 

 apparatus composing the mouth, and consisting of an 

 upper lip and tongue, a pair of horny mandibles 

 bearing a jointed palpus, a pair of internal* and 

 external nmxilhv, and three pairs of foot jaws grudu- 



* Hy somo accident M, Edwards lius di'scribc-il the Internal 

 m ,\HU' us the anterior foot Jnws, jmgr 954. 



ally increasing in i/.e, furnished with palpi, the largest 

 of which is the external pair fiisl mentioned above. 

 Beneath the antenna: is also placed a |MM ot apertures 

 which have been regarded as organs of hearing. The 

 members, which immediately succeed the external 

 foot-jaws constitute the legs, and are, also live pair in 

 number; they vary considerably in ai/.e ; those of the 

 lii -t pair are always prehensile, and terminated by a 

 didactyle and well-formed claw; in general the lour 

 posterior pairs of legs are .simply ambulatory or nata- 

 tory, they are never didaetyle. The abdomen N but 

 slightly developed, its length never exceeding three- 

 fourths of that of the entiie body, and its thickness 

 not equal to more than one-sixth or one-tenth of the 

 body, being in fact lamellose, and always clo-r|\ 

 applied to the sternal excavation. h is essentially 

 Composed of seven segments, but it often occurs that 

 some of these are so intimately soldered together, 

 that this part of the body appears to !,< only live, 

 four, or even three-jointed. In general it is much 

 larger in the females than in the males, beiny oval in 

 the former and somewhat triangular in the latter. 



We shall reserve for the article (.'u,\r., our observa- 

 tions upon the habits of this division, and shall here 

 simply give the chief subdivisions into which it has 

 been separated. This division comprises ;v very great 

 number of species, respecting the classification of 

 which cnutaceologistfl are not yet agreed. Dr. 

 Leach, followed by M. Desmarets, arranged the 

 groups according to the number of pieces of which 

 the abdomen is composed, both in the males and 

 females, a very simple plan, and one of very easy 

 application, but at the same time one which produce* 

 the most artificial results, some species belonging to 

 the same natural genus being removed thereby to 

 different families. M. l.aireillc, on the contrary, 

 founding his earlier classifications upon the pmial 

 form of the body and tin- disposition of the feet esta- 

 blished seven families, namely, the AV/"* ///* (paddle- 

 legged), Arqitcs (arched front), (J,n<nlrildtn-cs (four- 

 sided), Orbiculairct (orbicular formed), 'l'ri<iiigntftiret 

 (triangle formed), Cryptopodet (hidden leggea), and 

 Notojmdei (dorsal footed). Subsequently, however, 

 he took into consideration the form of the mouth ami 

 Home other characters in addition to the preceding, 

 the result whereof was the union of the Ka^t-urs and 

 Arqiu'-s into one family, and the modification of the 

 others. This latter classification has appeared the 

 most natural of any hitherto proposed to M. Edwards, 

 who (from a profound investigation of the structure of 

 the different groups) has been induced further to mo- 

 dify various portions, and to subdivide the lirarlii/nra 

 into only four great families, which he terms Oxy- 

 rhi/nc/it't, Cyclomctopct, Catametopft, and O.r//.v/o///r.v. 



The OXYRHYNCHI comprise the various species of 

 crabs known by the name of sea-spiders. The legs 

 are long, the shell more or less narrowed in front into 

 a beak, the epistomti (or part of the head between the 

 antenntc and mouth) very large and nearly square 

 This family comprises three tribes, Macro j>o<licnx, 

 Maicm, and Pertnenofieiu, 



The CYCI.OMETOPI has the shell very largo, regu- 

 larly curved in front and narrowed behind ; the legs 

 arc of moderate length; the epistoma is very slum, 

 and much wider than long. The abdomen of the 

 male occupies all the space between the hind legs. 

 This family comprises two tribes, the Ctincrrii-iis and 

 the Purtuniens. The former comprising three sub- 

 tribes, the Crifj)ti>j>t>t{cs, Arqnfs t and Qumlri/aterc*. 

 The type is the common edible crab. 



