202 EDIBLE CRUSTACEAKS OF NEW SOUTH WALES. 



River Crayfish. 

 Plate LI. 



Sides of tbe carapace on the hepatic and bi'ancliial regions furnished with 

 scattered conical spines, each enlarged at its base. Eostnim about as long 

 as the peduncles of the outer antenna^, pointed and furnished on each side with 

 four teeth ; its borders continued backwards for a short distance on the cara- 

 pace in the form of a ridge. A spine ])laced behind the middle of the orbit, 

 continued backwards into a similar shorter ridge. Scales ot the outer antennae 

 pointed. Merus of chelipedes with a row of sharp spines on its inner border, 

 two or three spines on its upper surface, and a row of small irregular teeth 

 on its upper border ; carpus with two or three prominent spines on its 

 inner surface — the first the longest — and one or two on the outer surface. 

 Hand with both borders armed Avith a row of short spines bent forwards, and 

 forming a double row on the external edge, and a single one on the internal. 

 roUowiug pairs of thoracic limbs with scattered spines. Segments of the 

 abdomen with four to ten large conical acute spines, except the sixth, which 

 usually has about a dozen smaller spines. Telson usually with aboiit eighteen 

 small spines. Appendages of sixth segment usually armed with about a 

 dozen small spines. 



Mr. Whitelegge considers that A. parraviatfejjsis and A. sy^neyensis are 

 only the young of A. serratus, which is a Tery variable species. 



The Eiver Crayfish is but rarely seen in the Sydney market, but is largely 

 used as food by the residents on the banks of the rivers, in which it abounds, 

 during the winter months, when they are in their best condition and most 

 readily caught; they are excellent eating and grow to about a foot in length. 



Family IIL-VENMIBM. 

 Three anterior pairs of legs chelate, longer than the rest, and more or 

 less stronger. 



Genus— PEN^US. 



Pencvns, Fabr. Suppl. Eut. Syst. 1798. 



Three anterior pairs of feet linear : two posterior pairs not annulated. 

 Carapace with a long ensiform rostrum. Abdominal feet with two lamina;. 

 External maxillij)edes palpigerous. 



PEN^US CAIS'ALICULATUS. 



PaJcemon canaliculcdus, Olivier, Encycl. viii. p. 6G0, 1811. 



JPencBUs canaliculcdus, Milue-Edw. Hist. Nat. Crust, ii. p. 414, 1837; 



Do Haan, Faun. Japon. Crust, p. 190, 1849 ; Miers, Proc. Zool. Soc. 



1878, p. 298 ; Haswell, Proc. Linn. Soc. N. S. "Wales, iv. 1879, p. 38 ; 



and Aust. Malacostr. p. 198, 1882. 

 PencEUs plelejus, Hess, Arch, f . Nat. xxxi. p. 168, pi. vii. fig. 19. 



Sand Prawn. 

 A median crest, mesially grooved behind, and witli a deep longitudinal 

 groove on either side of it continued from the base of the rostrum to the 

 posterior border of the carapace. Kostrum as long as the peduncles of the 

 antennules, curved slightly upwards towards the acute extremity armed with 

 10-12 teeth above and one below. A very strong tooth on the anterior 

 border of the carapace above the insertion of the antennas ; a second, much 



