198 EDIBLE CEUSTACEANS OP NEW SOUTH WALES. 



Class.— CRUSTACEA. 



?A 



Invertebrate animals, distinguished by the possession o£ a more or less 

 liard, jointed, external crust, or exoskeletou, nearly all living habitually in 

 water, and breathing by means of gills. 



Of the Crustacea the large group of the Malacostraca are distinguished 

 from the rest (the Entomostraca) by the number of the segments of the 

 body, of which there are always twenty, except in certain cases in which 

 amalgamation or abortion of one or more of the segments has taken place. 



Tribe I.-BRACHYURA. 



Abdomen short, inllexed beneath the thorax, without swimmerets, and 

 with no appendages on the penultimate segment. Carapace greatly developed, 

 forming wide branchial chambers above the bases of the legs. Sternum 

 never linear ; vulvae situated on the sternum. Antcnnse with the flagella 

 usually very short, especially those of the inner pair, which are lodged in 

 distinct cavities. External maxillipedes oj)erculiform. Buccal cavity 

 distinctly defined in front. 



Subtribe. — Cyclometopa. 



Carapace usually transverse, wide in front, regularly arcuate anteriorly 

 (sometimes quadrate or suborbicular), never acuminate or rostrate. Epistome 

 short, transverse. Internal antenna) usually transversely plicate. 



Family I.-PORTUNID^. 



Carapace depressed, usually more or -less hexagonal in shape, never very 

 convex. Antero-lateral margins with well defined acute teeth. Inner ramus 

 of the first (innermost) pair of maxillipedes with an internal lobe. Margin 

 of the efferent branchial channel usually defined by a longitudinal ridge on 

 each side of the prelabial plate or palate. Filth pair of ambulatory legs 

 natatorial, their terminal joint oval, expanded, and lamellate. 



Genus I.— NEPTUNUS. 



Ifeptumis, De Haan, Eaun. Japon. Crust, p. 7, 1835. 



Carapace very wide, with transverse granulous lines. Latero-anterior 

 margins with nine or more teeth (including the external oi'bital angle), the 

 last tooth much the longest. Eront wide and divided into five or six teeth. 

 Elagellum of external antenna; placed in the internal orbital hiatus. 

 External maxillipedes short. Anterior legs long : arm with acute tubercles 

 upon the anterior margin : hand nearly prismatic, with longitudinal ridges 

 giving rise above to spiniform tubercles. Thigh of the swimming legs with 

 the lower margin usually destitute of spines. 



• All the technical diagnoses are taken from Dr. Haswell's " Catalogue of Australian Crustacea," the 

 Bpecies selected being those most commonly found in the Sydney market. 



