130 F. A. PARSONS ON A NEW HYDROID POLYP. 



low a temperature would interfere with the development of medusas 

 I cannot say, but should think it probable. 



There is one point which I omitted when speaking of its powers 

 of offence. I am inclined to believe that it has defensive powers 

 also. This idea occurred to me from seeing a rotifer blunder 

 head first against the trunk of one of these polyps. The rotifer 

 backed off instantly with its rotary organs retracted, and had every 

 appearance of being seriously hurt ; in fact, I thought it had re- 

 ceived a death blow. I watched it for some time, but it ultimately 

 recovered and swam off as though nothing had happened. 



In concluding these remarks I must apologise for the very 

 rough form in which they are presented, and for the absence of 

 more solid information than I have been able to give. I have 

 kept no notes, and my remarks are given entirely from memory ; 

 some of the sketches are also made from recollection of the objects. 

 I may therefore not have been quite so precise on some points as 

 could be desired ; my excuse is that I have not had the leisure 

 necessary for working out the matter in a more satisfactory 

 manner ; but I thought the members might like to know something 

 concerning the polyp, the first discovery of which is due to the 

 Club Excursions. I shall continue my observations, and if I dis- 

 cover anything fresh of sufficient interest I may on a future occa- 

 sion trespass on your patience. 



DESCRIPTION OF PLATE VI. 



Figures 1 to 9 may be considered as diagrams only, having been drawn 

 entirely from memory. With the exception of Fig. 5 they approximately 

 represent the appearauce under the inch objective and B eye-piece. 



Figs. 1, 2, 3, 4, represent the early stages in the development of the polyp. 



Fig. 5 is an enlarged sketch of a nematocyst or thread-cell, as seen under 

 the quarter-inch objective and B eye-piece. 



Figs. 6, 7, and 8 show various other forms referred to in the paper. 



Fig. 9 is a trifid form with a fourth polyp budding out at a. 



Fig. 10 shows a form similar to that shown at Fig. 3, and 



Figs. 12, 13, and 14 three different stages, bipartite, tripartite, and 

 quadripartite in close proximity ; also variation in form from Figs. 5, 7, 8, 

 and 11. 



