198 AUSTEALIAN HALACOSTRACA. 



squame, with a spinif orm outer apex ; flagellum not longer than 

 the peduncle. Appendages of the antennae not shorter than the 

 rostrum. Third, fourth, and fifth pairs of feet subprehensile 

 the dactylus capable of being retracted against the side of the 

 penultimate joint. Abdomen strongly geniculate, the third 

 segment armed with a very obtuse carina, the sixth segment very 

 long. Subpellucid, ornamented with yellow lines and black dots. 

 Length 1 in. [Sti)nps.~] 



Port Jackson. 



Sub-Tribe Pen.eioea. 



Carapace without sutures. External antennae with a large 

 basal squame. Feet of the first and second pairs not thicker 

 than the third, the third often rather thicker, longer, and chelate ; 

 rarely all the legs weak and slender, the third either obsoletely 

 chelate or completely vergiform. 



Family PEXMIDJE. 



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

 more or less stronger. 



Genus Pejt-EUS, Latr. 



Three anterior pairs of feet linear ; two posterior pairs not 

 annulated. Carapace with a long ensiform rostrum. Abdominal 

 feet with two laminae. External maxillipedes palpigerous. 



370. Penseus canaliculatus. 



Palcemon canaliculatus, Olivier, Encycl., viii., p. 600 (1811). 



Penceus canal iculatus, M.-Edw., Hist. Nat. Crust., ii., p. 411 

 (ls;J7) ; DeHaan, Eaun. Japon., Crust., p. 190(1819); E. J. 

 Miers, P. Z. S., 1878, p. 298 ; Has well, Proc. Linn. Soc. N.S/W., 

 Vol. iv., p. 38 (1879). 



Penceus plebejus, Hess, Arch, fur Nat., Vol. xxxi., p. 108, 

 pi. vii., fig. 19. 



A median crest, mesial ly grooved behind, and with a deep 

 longitudinal groove on either side of it continued from the base 

 of the rostrum to the posterior border of the carapace. Rostrum 



