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JAPANESE SPECIES OF THE GENUS Penaeus. 



BY 



K. KISHINOUYE. 



With PI. I— IX. 



Prawns belonging to the genus Penaeus are the most important 

 crustaceans in Japan. They are highly prized and extensively used 

 as food and bait and dried prawns annually exported to China amount 

 to about 900,000 kilogrammes in weight and about 200,000 yen in 

 value. The dried prawns almost exclusively belong to the genus 

 Penaeus. 



Prawns live in inshore waters, especially in bays and inlets of 

 sandy or muddy bottom, mostly in the depth of less than 60 metres. 

 They are very abundantly captured with small trawls, dredges, fyke- 

 nets, etc. in the Inland Sea, Bay of Ise, Bay of Tokyo and many 

 other places round our coast. However, they are scarce on the coast 

 of the Japan Sea and on the northeastern coast, so that they seem 

 to prefer warm water. 



Prawns generally feed on living or dead animals, such as Crustacea 

 (Gammarus, Caprella, etc), Vermes, Echinoderms, Mollusca (especially 

 small immature Gastropoda and 'Lamellibranchiata) and sometimes fish. 

 Some species, especially Penaeiis Joyneri prefer microspical algae: The 

 shell of such species is soft. When they are kept alive in ponds, they 

 attack and devour each other. In such cases newly moulted creatures 

 easily fall the victim. . 



The growth of , prawns is very rapid., Small prawns reach matu- 



