rity when one year old, and most ol them, I believe, die out after 

 spawning. Large prawns such as Penaeus cauaHculatus, P. semisttfefrit+s, 

 etc reach maturity alter two years and they do not die after spawning. 

 Some large species attain the size of about 27 cm. 



The male seems to develop more slowly than the female. The 

 former becomes mature and attains the maximum size of growth a t a 

 smaller size than the latter. The difference between the biological 

 minimum size and the maximum size of growth is always nearly equal 

 in both the sexes of the same species and this difference is greater 

 in the species which maintain longer life. Generally speaking females 

 are larger in size, have the larger carapace and the longer and more 

 curved rostrum when compared with males. 



The ovary is composed of a pair of long, thick tubes, running from 

 the root of the rostrum nearly to the tail segment. They give off 

 side branches and the oviduct at the thoracic region, and there just 

 before the heart they are connected together by a transverse com- 

 missure with each other. Generally they ripen at the end of spring 

 and spawning takes place in summer and autumn. They are very 

 slender, colorless and nearly transparent when their reproductive ele- 

 ments are immature ; but when these elements gradually begin to ripen 

 they become opaque and yellowish in color and finally become rich 

 green in color and increase in thickness. Eggs are discharged from 

 time to time as they ripen. The oviducts are extremely short and 

 thin-walled. 



The testis is a furcated horse-shoe shaped gland in the thoracie 

 region. It lies partly surrounding and partly beneath the heart. The 

 gland is flat, colorless and translucent. 



Some species have a spermatophore at the end of the ductus ejacu- 

 latorius. In Penaeus canaliculars > P. ashiaka and P. acrvirostris males 

 have always a pair of spermatophores and copulate throughout the 

 year. Immature females not unfrequently contain spermatop'hofes or 



