A FEW CCELENTERATES OF WOODS HOLL. 99 



identical with the European, it should call for very convincing 

 evidence to decide to the contrary. I do not overlook the fact 

 that Professor Nutting, who has seen the European species, be- 

 lieves that Agassiz's early decision was correct, but the only evi- 

 dence he cites in its favor is the " larger hydranths and less num- 

 ber of tentacles," of the English species, both of which charac- 

 ters are exceedingly variable ones, and hardly admissible alone 

 from which to predicate specific distinction. 



In some of the colonies collected during the summer I thought 

 for a time that some such differences as Nutting indicated were 

 present, particularly on those taken from piles. But upon a com- 

 parison of other colonies they were entirely lacking ; and still 

 other comparisons showed such apparently indistinguishable inter- 

 gradations of characters that I was compelled to regard them as 

 too variable to warrant the establishment of an independent 

 species. I must therefore return to my earlier impression with 

 increasing conviction, namely, that our species of Hydr actinia is 

 to be regarded as identical with that of European waters, and is 

 therefore H. echinaia Fleming, and not H. polyclina Agassiz. 



Cordylophora. — This hydroid is known to have a very wide 

 range of distribution, but so far as I recall at this time only a 

 single species is known, namely, C. lacustris Allman. It was 

 first found at Woods Holl by Professor Morrill in 1899, in 

 Nobska pond, who kindly turned it over to me for identification. 



Since then I have taken it in several similar ponds in the 

 region and near Falmouth, and in fresh or brackish ponds on 

 Marthas Vineyard. Indeed the hydroid seems to be quite gen- 

 erally distributed throughout the region. The more common 

 habitat is on fragments of rock, or on bits of submerged sticks, 

 eel grass, etc. Occasionally it forms large and rather complex 

 colonies, the hydrorhiza forming an intricate network from which 

 branching stems arise to a height of about an inch or slightly 

 less. The reproductive season seems to be chiefly in spring or 

 early summer, and sparingly in July. Colonies have been found 

 later, September or October, but with no signs of gonophores. 

 As I have pointed out in an earlier paper [Zo'dl. Bull., Vol. I., p. 

 205), it lives well under the artificial conditions of aquaria, but only 



