62 N. AnnandALE : The Fauna of Brackish Ponds. [VOL. I, 



of these organisms in the bodies of the Actinians is probablj^ con- 

 nected with biological differences in the hosts. 



Biology. 



Relations to environment. — 



Stoliczka found the original specimens of the species living 

 attached to logs of wood ; he therefore suggested that the}^ should 

 be called Lignacalephse. I have recently found specimens of the 

 typical form ensconsed in the dead shells of barnacles fixed to 

 iron posts in the Matla estuary. Stoliczka noted that the species, 

 as he knew it, frequently inserted its basal disk into cavities in the 

 logs to which it attached ; both in the case of my specimens and 

 of his, the basal disk was extended somewhat beyond the periphery 

 of the column to cover the base of the cavity in which the animal 

 was stationed. In circumstances in which it is impossible for the 

 Actinian to protect itself by entering a cavit}^ already formed, for 

 example when it is in a glass vessel, it constructs a protecting 

 sheath for itself out of such objects as filaments of the alga; 

 which grow in its natural habitat. This habit has been exemplified 

 by individuals of both forms recently living in captivit}^ in 

 Calcutta, especially by full}^ grown individuals of the typical form 

 and b}^ young individuals of the new race. I was able, in the 

 case of one example of the latter, to observe the production of the 

 sheath. The animal had been removed from the aquarium and 

 placed in a watchglass full of water, and was being examined 

 under a fairly high power of the microscope. After a few minutes 

 of complete contraction its column grew slightly longer and at 

 the same time a large number of stinging- threads were emitted 

 from the upper part of this region of the body. These were 

 of simple structure, devoid of barbs. The}^ did not remain still 

 after being set free, but displa3^ed a rapid corkscrew motion 

 closely resembling that of many spermatozoa and were thus carried 

 through the water for a short distance round the Actinian, from 

 which they did not recede. A quantity of mucus was also 

 secreted from the exterior of the column. The rapid movements of 

 the threads did not last for more than a few minutes, but, as the}' 

 ceased, the threads became matted together with the slime, which 

 retained any extraneous substances that chanced to come in contact 

 with it. Larger examples of the new race, examined as the}' 

 were taken, had particles of the mud from which they had been 

 removed adhering to them, probably for the same reason ; but 

 in all cases the external coating thus formed was of an extremely 

 evanescent and flimsy nature. 



As I have already pointed out, there are few solid bodies at pre- 

 sent to be found in the ponds at Port Canning I have searched 

 them in vain for specimens of the typical form of the species, 

 which was living in one of them thirty-nine years ago, when the 

 logs of wood were there. Representatives of the new race now 

 abound, however, in the ponds, with the exception of the two 



