412 



CRUSTACEA. 



THE FIKST FAMILY* OF BECAPODA,- 



Decapoda Drachyura {Kleislaijnaiha, Fahricius), — 



Has the tail (or post-aljcloiiicii) sliorttT than the thorax, without appeiuhiges or swimmerets at its 

 extreiiiity, and in a stati_' of re&t fohh^I beneath the breast, and lodged in a sternal cavity. 



It is triangnlar in the males, but rounded 

 and swollen in the femalesf, and is furnished 

 in the former with four or two appendages at 

 tlic base [on tlie inside], whilst in the female 

 it has four pair of donldc filaments employed 

 incarryiiig the eggs, and whieli are analogous 

 to tlie swimming snb-abdominal appendages of 

 the Macrura. The antenmc are small ; the 

 intermediate pair, generally lodged in a cavity 

 beneath tlie fore-margin of the carapax, are 

 terminated by two very short [articulated] 

 filaments. The peduncles of the eyes are 

 larger than in the Macrura, The first pair of 

 legs is terminated by a claw. The branchirc 

 are arranged in a single row in the form of 

 ]tyramidal plates, composed of a great num- 

 ber of minute leaflets spread one upon the 

 other : tiie fuot-jaws are ordinarily shorter 

 and broader thau in the Decapods, the outer pair forming a hiud of labium. 

 This family may be regarded as coiislituting the single geuus 



Fi^. ].- 



body, 



et's 1 A. ■ 



; d, outer foot ja 



.-ilblc Crab), upprr side atJ.i utidti 

 ;d.— .(, l.-ituritl AiitunnH; 0. IiiIlt 

 "•' ; ^if> i'l ''. '"'^c of tlic live p^ir; 



Cancer, — 



Comprising the numerous species of cral>s [and consisting of a portion only of the Linn:::an genus 

 Cancer, divisible into se\T'u sections and a great nnmljer <jf minor divisions, regarded by reeent aulbors 

 as genera]. Of these the majority have the legs attached at the sides of the breast, and always ex- 

 posed. The species thus chaiacterized coustitute the first five sections, Pinnipedcs, Areuata, Quadri- 

 latera, Orbiculata^ and Trigona.:J: 



hnti long perplexed Crustaceologists ; and M'Leay, in order 

 liis quifinrinn sysltm to the:ie animals, lius divided tlie DcuHpotla into 

 five tribes, Ti-truijoiiostoina and Trigonostoma (cooiposini; the 

 Bracliyura), and Aiioiiiura, Siirobr»incliia, and Ciirideft (coinpoiiiiff 

 the iMacruara).— ///«i./r. Auvidos. of Sriuth Africa, No. 3.] 



* Tlii; gruops thus indicated are founded upon a general survey of 

 liiipnriTint auatomiciil characters, and generally correspond with the 

 Liiiria.'aii genera, and sometimes also to those of tlie carliiT works of 

 Fabriciuii. These families are bcrc of greater extent than in my 

 other writings ; but if we regard tliese as primary ordinal divisions, 

 and Uie groups here called tribes as fsmilica, the arrangeuieiiL will be 

 found i-,ssei;tially identicnl. In the K^iniu manner tht- Bub^enera here 

 indic:itod ought, iti a move ih tailed arrangement, to bt regarded as 

 (jcnL-ra, and thus, although Ll.c Deeapoda are liere only divided into 

 two gL-nera, it would be correet, ill order to bring the syatem to the 

 level of our present knnwlvdBC, and in ..rdcr to diminish the vast 

 nu(iil)er ol sub-genera, to convert the sections into tribes or genera, 

 which might then be divided into subgenera. 



■j- Tlic apiiarent number of segments is gencrnliy seven, varying 

 oceasionally in the sexes of the same Bjieeies, in M'lit( li eiise the 

 females have the least number. Dr. Leach nia<le great u.se of this 

 churaeier, but it nppeais to me to be too uDimport.-int. 



X [Lalreille regarded this arrangement of the Crabs liere given as 

 irtifieial in many respects, and he had modified it not only in his 

 FaiiiiUrs NiitiirrllP.s, in which the tribes here given were introduced 

 but ilieir relative pONition altered, but in his Buhscqurnt C'oiirs 

 d-F.,.(<j„.vl'jf^ri,: [,,, proposed ano Uer arrangcmeiit uf ihc order, as 

 follows:— 

 Sijution 1. llomocbelea, claws of cr(ual size in both scies. 



Division 1. All the feet attached to the body in the same line. 



Tribes.— 1. Quadrilatera, '2. Areuata, 3. Piunipcdes, ■!. Christi- 

 niani, 5. Cryptopodu, 



pti 



Tribe.— G. Xi, 

 I 2. Heterudiel 



of the male; 



of the 



Elit 



nail, an. 



■ntioncd, adopted tin 

 juGUtly led to diatribi 

 Milne Edwards, ho« 

 lurse of publication, 

 I it more natural to t 



fither doi 



abdr. 



has, from ana 

 ^parate the Br." 



Division 1. All the legs in the s 

 Tribes.— 7- Orbieulata, 8. T 

 Division 2. Hind pairs of legs 

 abortive. 



Tribe.— 9. Hypopthalma, 



Dr. Leach, as above 

 segments, and was eon 

 more numerous familie 

 des Crust'icis, now in 

 considerations, coiiside 

 into only (our great faniilies. 



1. The Oxyrhyeha (Trigona, Latr. or the families Maiada;, Lithodi. 

 and Macropodiadae of Leach), consisting of the sea spiders or tli 

 backed crabs, the legs being long, tht carapax narrowed into a j 

 in front, the epistoina very large and nearly square. (Three tr 

 Macropodiens, Maiens.and Parthenopiens) . 



2. The Cycloinetopii (or the Canceridic, Portunidif, and Pilum; 

 of Leach) I carapax very large, arched in front, narrowed behind, h g; 

 moderately long, epistoina very short, transverse. (Two tribes 

 1. Caneeriens, composed of three sub-tribes, Cryptopoda, Areuata 

 and Quadrilatera ; and, 2. P.irtuniens or Pinnipedcs). 



3. 'i'lie (.latametopa (Oeypodiadie, Leach}, having the carapax quad 

 rilnieral or ovoid, the front transverse and knotted, cpistoma verj 

 short. 



4. The Oxystoma (Cnrysti.lie and Lencsi^idie, l.r:.rh) , Mithtlu' slirl 

 orbicular and arched in front, whicli is not iioinied, cpiitoma olj- 

 solctc. 



Itc 



