46 Proceedings of the Royal Physical Society. 



derm with which it and the scleroderm were covered, and 

 which could only be removed by directing a strong stream 

 of water against it. 



(5.) Coryne ferox (n. sp.), T. S. W. 



Polypary creeping. Polyp-stalks single, smooth. Ten- 

 tacles, thick, short, having the capitate cluster of 

 thread-cells scarcely larger than the width of the 

 tentacle. Medusoids developed beneath the tentacles 

 similar to those of C decipiens. 

 This Coryne resembles C. decipiens (Dujardin) in the 

 shape and mode of development of the medusoids, but it 

 differs from that zoophyte in its more robust and clumsy 

 habit. The tentacles of C. decipiens are long, tapering, 

 and capped with large bulbs of thread-cells. Those of C. 

 ferox are short, nearly of equal thickness throughout, and 

 though they are surmounted with a cluster of thread-cells, 

 the thread-cells are so few in number, that the tentacles can 

 scarcely be called "capitate." A delicate epidermis of colleto- 

 derm passes over the whole body and tentacles of the polyp, 

 which causes it to assume a dirty appearance, as it often 

 serves to support a downy growth of very minute algse. C. 

 decipiens is the hardiest of all the hydroidse ; I have known 

 a colony of it to live for six years in captivity, whereas C. 

 ferox seldom survives more than a few days after having 

 been removed from the sea. 



III. On Ophrydium versatile, Ehr. By W. R. M'Nab, Esq. 



The Ophrydium versatile is one of the most curious of all 

 the infusoria, occurring as it does in large gelatinous masses of 

 a greenish colour, which are sometimes adherent to the steins 

 of aquatic plants, but often free, and floating on the water, 

 like masses of frog's spawn, for which it has been mistaken. 

 It is found in considerable quantity in several ponds near 

 Edinburgh ; and from its abundance in the Botanic Garden 

 pond, the observations here recorded were made, an abundant 

 supply being at all times at hand. The gelatinous masses 

 contain great numbers of the individual Ophrydia, which 



