DECAPODA. 



4-7 



Tribe A [Aschizopoda, Wcstw.]. — Those which, in the proportions, forms, and uses of the feet, the 

 anterior, or at least the second, pair being chelifcrous, and which carrying their eggs beneath their 

 tails, approach the Brachyura, and which are ordinarily known under the names of Lobsters, Cray- 

 fish, Prawns, and Shrimps. Divisible into four sections: — 1. Anomala; 2. Locustae ; 3. Astacini ; 4. 

 Carides. 



Tribe B [Schizopoda, Latr.]. — Those which have the legs slender and filamentous, accompanied bv 

 an external articulated branch as long as the limbs, which thus appear doubled in number; fitted for 

 swimming, and not chelifcrous, the eggs being carried beneath them, and not under the tail. [Opossum 

 Shrimps.]* 



The first section [of the tribe Aschizopoda], or the Anomai.a. — The two or four hind legs are always 

 much smaller than the preceding. The under side of the tail never presents more than four pairs of 

 appendages, or false legs.f The lateral swimming-pieces at the extremity of the tail, or the parts which 

 represent them, are thrown back at its sides, so as not to form with the terminal segment a fan-like 

 swimmeret. The ocular peduncles are generally longer than those of the Macroura of the following 

 sections. [Two subsections, Hippides and Paguriens.] 



The subsection Hippides (Latr.) has all the upper teguments of the body solid. The two fore-legs 

 either terminate in a nionodactyle or fingerless hand, like a plate, or they terminate in a point. The 

 six or four following legs terminate in a swimming-plate. The two terminal legs arc filiform, folded 

 back, and situated at the lower base of the tail, which is suddenly narrowed after the first segment, 

 which is short and broad, and of which the last is in the form of a long triangle. The lateral appen- 

 dages of the penultimate segment are in the form of bent swimming-plates. The sub-abdominal 

 appendages are four pairs, and formed of a very slender filiform stem. The antennae are very pilose 

 and ciliated, the lateral at first approaching the intermediate, and then being bent outwards. 



Albunea, Fabr., comprises a single species from the Indian Seas (Cancer St/mnisfa t Linn.) 

 [a singularly formed animal], with long, setaceous, intermediate antennae; the carapax rlat, 

 nearly square, rounded at the posterior angles; a pair of very compressed, triangular, 

 monodactyle fore-legs, — the three following pairs terminated by a flat, sickle-shaped joint. 



Etippa, Fabr., Bmerita, Gronovius, lias the antennae short, the intermediate with two fila- 

 ments longer than the external; the two fore-legs terminated by a very compressed claw, 

 without fingers ; the carapax ovoid. Type, Cancer Emeritus, Linn. Indian Seas. 



Remipes, Latr., differs from the last in the four antennae being very short, and nearly of 

 equal length ; the ocular peduncles very short, and in some other particulars. Type, Ii. 

 tettudinarius, Latr. From the seas of New Holland. 



The subsection Paguriens has the teguments but slightly crustaceous ; and 

 the tail i3 generally soft, bag-like, and bent. The two fore-legs terminate in a 

 didactyle claw; the four following terminate in a point; and the four posterior 

 much shorter, in a small didactyle claw. The first joint of the peduncle of the 

 lateral antennae presents an appendage ending in a point, or in form of a spine. 

 These Crustacea (which the Greeks named Carcinion, and the Romans Cancelli) 

 live, for the most put, in empty univalve shells. The tail, except in Birgus, only presents (and tli.it 

 in the female alone) three false legs placed on one of the sides, each divided into two filiform villose 

 branches. The three terminal segments are suddenly narrowed. 



Birgtu, Leacii, baa the tail solid, suborbicular, with two rows of plate-like appendagea on the under side. The 



fourth pair of lees is but little smaller than the preceding ; the two posterior pair are [very small, snd] bidden in 



i groove in the extremity of the carapax. The carapax is in tin- shape of a reversed heart, being pointed in front. 



( in account of their large size, the solid consistence of their teguments, ami the form of the tail, these Crabs me 



not able to lodge in shells, but must retire to crevices in the rocks, or hide themselves in borrows in tl artli. 



Fig. 6. — Iteniipej testu- 

 diuariua. 



• 'It is hire |.rnprr to observe, that In the recent arrangement! of 

 Milne Rdwudi and M'Leay, tl,e lerentb and last section, Xotopoda, 

 of LatrcUle'a arrangement ol the BrechyiirA, and bla Ant aectlon oi 

 the Macrovra, Anomala, constitute one of the ilirn- primary drrialona 

 of the Dtrapoda, IbrnlBf, as nay be rendu v perceived, the peuage 

 between the Braebjan and theMacnrarei and, aa conatantlr ocean 



where nature pi.se, BrOn DM tfpa "( t.irni to another, we find emonfal 

 tl fee inlmala some of the nOBI ■ trihiDg aoumallea which occur in the 

 t'-JUi — hence the name Aiiomoiira, or anomalous-tailed Crabs — 

 which ere divided he M. hd*ar,ls ii.' ' lonf or fntni. 



1 ri — 1. The \| • rura, or those destitute uf a terminal nril 

 including the Mr H illene, Ranlnlena, and PaetoUena t and, 



2. The Ptcryiiurv or those which have a pair of movrahlc appendages 



at the extrtmltj ol the tail, tnelntttng the Porcell »a t H 



and hururlene. Thtull will appeal thai the fortni Ui uiorc 



analogous to the Mrachvura, and the Utter to the Ma. roura.) 



t With the ctception of the interior pair, these appendage* are 



either radlmenta] or obaolef the male.,— a pecullaritj v» hli 



curs also in the Galatbaa, Srvllari, >nJ Pallnori. We »„ also o»> 

 three genera, the ewttatnerete at n»- 



llie body are more slimier, or lieirlv ine-ittirsnnils, at the pi- • r 



margin. In • than, the portion oi the thorax 



Kind pair ui le.|. form! a .orl of pedum ic, «1-HC4 

 ii of le^s appcan to be attached to the tail. 



I I. 



