-ro^v 



63 



NOTES on CUCUMAKIA PLANCI. 



By Herbert C. Chadwick. 



With Plate I. 



[Read December 12tli, 1890.] 



On June 26th last, while dredging in the Turbot Hole, off 

 Puffin Island, I obtained about twenty specimens of the 

 Holothurian Cucumaria planci. The majority of these 

 were of small size, not more than five or six exceeding an 

 inch in length. Selecting three of the largest and most 

 vigorous looking, I placed them in a glass jar holding about 

 a pint of water, in order to watch their habits. Two days 

 later one of the specimens discharged about fifty ova. 

 These were rather less than 50 of an inch in diameter, pale 

 cream in colour and quite opaque. Each ovum had a 

 mucilaginous investment which, after some hours contact 

 with the surrounding water became distinctly thicker. 

 During the following two or three days I had a number 

 of ova under observation, but beyond the extrusion in one 

 instance of two polar bodies, I saw no signs of develop- 

 ment. 



On July 6th one of the adult specimens assumed the 

 condition represented in fig. 1, and remained almost 

 motionless until early on the morning of the 8th. The 

 middle portion of the body then became much more at- 

 tenuated, and a slowly elongating rupture, of which an 

 enlarged representation is given in fig. 2, brought the 

 tightly stretched intestine into view. Then the two ends 

 snapped asunder, and the anterior slowly crawled onward, 



