48 LIFE BY THE SEASHORE. 







intervention of the swimming-bell, they are carried away 

 some distance from the parent colony. The swimming-bell 

 seems to exist only that it may perform this function of 

 carrying away the eggs, and in structure it is, as it were, a 

 zooid which has become adapted for a free-swimming life in 

 the open water. Like the zooid it has tentacles, but these 

 are few in number (only four), and relatively very long. 

 They hang down from the margin of the bell, and are 

 abundantly supplied with stinging threads. It should be 

 noticed that though Sarsia seems large in comparison with 

 the size of the zooids of Syncoryne it may have a diameter 

 of three-quarters of an inch yet its bulk is largely due to 

 the contained jelly, which is again largely water. 



The last member of the Gymnoblastea which \ve shall 

 consider is the large and beautiful Tubularia indivisa, which 

 again produces sporosacs and not swimming-bells. It is a 

 form in which the stems are sometimes as much as a foot 

 long, and which is especially common on piers and landing 

 stages. It also occurs on rock surfaces and stones on the 

 shore, but usually near low-water mark. If, as sometimes 

 happens, you know that it is growing in abundance on some 

 rocky ledge or pier support not readily accessible with the 

 resources at hand, an indirect method of obtaining speci- 

 mens may be tried. That is, you may anchor by means of a 

 stone a log of wood in the vicinity of the spot, and you will 

 probably find that in a few weeks the log will become 

 covered with a luxuriant growth of zoophytes, including the 

 desired Tubularia. I have seen singularly beautiful speci- 

 mens obtained in this way. The prudent naturalist will, of 

 course, also not neglect such possible sources of supply as 

 buoys, which are often taken up regularly to be cleaned, old 

 boats left anchored in quiet coves, and wreckage. 



One of the special peculiarities of Tubularia, by which it 

 is distinguished from any other zoophyte we have described, 

 is the arrangement of the tentacles. These are arranged in 

 two circles, of which the one (a in Fig. 16) surrounds the 

 mouth and consists of very short tentacles, while the other 

 (b in Fig. 16), whose members are long, is placed at a 

 considerable distance below the mouth. Between the two 

 circles are placed the sporosacs (c in Fig. 16), which in 

 T. indivisa are borne on branched stalks, and hang down 



