II 



PENAEUS CANALICULARS. 



(Pi. i) 



Penaeus canaliculatus, Olivier, Encycl. meth. Nat. Hist, viii (1.811.), 

 M-Edw., Hist. Nat. Crust, ii (1837); de Haan, Fauna Japon. Crust 

 (1849); Sp. Bate, Challenger Rep. Crust. Macrura (1888); Ortmann, 

 Zool. Jahrbuch. Abth. Syst. p. 448 (1890). 



The shell smooth, thick and hard. The rostrum slightly curved, 

 8 or 9, rarely 10 dentate above and toothed below. It is a little 

 longer than the peduncle of the first antennae. Continuous to the 

 rostral kiel, there is a grooved kiel, which reaches nearly to the 

 posterior margin of the carapace. On each side of the rostrum and 

 the kiel, there is a groove which also reaches nearly to the posterior 

 margin of the carapace. The flagellae of the first pair of the antennae 

 are very short, almost equal to the length of the two distal segments 

 of the peduncle. The pereiopoda are rather thick and robust. The 

 basis of the first and second pairs of pereipoda is provided with a 

 spine. The telson with three pairs of small movable spines. 



The thelycum, the external wall of the seminal receptacle, has 

 the pocket-like appearance externally, as the two lateral plates are 

 united in the median line (PI. VII, 1 A, 1 B). The cavity of the 

 receptacle is single. The wall of the receptacle, external as well as 

 internal, is not calcified. 



The petasrna is simply folded longitudinally (PI. VII, i). The 

 outer rim is thick, calcified and blunt at the distal end. The inner 

 lamina thin, membranaceous and much prolonged posteriorly and it is 

 differentiated to a free, thick and fleshy portion at the anterior end. 



The spermatophore is provided with a wing-shaped appendage 

 which stretches out of the seminal receptacle in a pair (PI. VII, 1 C). 



