Notes on the Development of Cucumaria 

 echinata. 



By 



Hiroshi Ohshima, 



Fifth High School, Kumamoto. 

 With Plate V. 



From the fact that the embryo is quite opaque and that the 

 transformation proceeds very rapidly, the study of the development of 

 Cucumaria is not an easy task. Though SELENICA, Ludwig and some 

 others have elucidated many important features upon the subject, our 

 knowledge is still very' far from being satisfactory, especially about 

 the early development of the ambulacral system and the formation of 

 the body-cavities. I have endeavored to make clear these points in 

 Cucumaria echinata, which abounds in Misaki. « 



In this paper I give a preliminary account of so .ne of the results 

 of my observations. This holothurian develops in a way not very 

 different from the allied forms of Europe, such as C. planci, C. normani, 

 etc. Detailed comparison with those forms and discussion on the 

 literature will be made in the definitive paper to be published later. 



Spawning. 



The breeding season of Cucumaria echinata begins, in the vicinity 

 of Misaki, in the middle of June and lasts till the early part of August. 

 Freshly obtained mature animals kept in a glass jar will begin to 

 pour out reproductive elements in the evening of the same day. The 

 poured out spermatic fluid forms white cloudy strings, five or six in 



