128 



F. A. PARSONS ON A NEW HYDROID POLYP. 



just able to detect the threads coiled up in the little papilla-like 

 receptacles on the head of the polyp. 



Besides the simple form I found three other forms ; these were 

 evidently further developments, but how brought about I have not 

 been able to determine, for I have not discovered any interme- 

 diate stages, though 1 hope I may yet be able to find them. If I 

 may be allowed to speculate — though it is unsafe to do so — I should 

 think it probable that the second polyp is developed from the base 

 of the first, thus causing the erect position to be changed to a 

 recumbent one. The tripartite and quadripartite forms are prob- 

 ably developed in the same manner as the bipartite form.* 



The method of attachment of the polyps I have not been able 

 to make out; they do not appear to have anything like the ad- 

 herent disc or foot of the hydra, though there is probably some 

 approach to that organ ; neither have I been able to discover that 

 it has any powers of locomotion, though after the collapse of the 

 sponge skeleton I found a polyp attached to some rootlets. 

 The only motion I have observed is a sluggish one, the 

 animal occasionally bending its body sideways as if searching 

 for food, remaining motionless for a considerable period, and pre- 

 senting altogether a harmless appearance. This appearance is, how- 

 ever, utterly deceptive, for its powers of paralysing its prey 

 equal, if they do not surpass, those of the hydra, though it 

 has not its activity, otherwise it would be impossible, in the 

 absence of tentacles, for it to obtain food ; any small animalcule 

 coming in contact with the head must be instantly paralysed, 

 else, on finding itself hurt it would dart away out of reach. 

 As regards its method of feeding I was for some time in doubt ; 

 I could not detect any mouth, and as I found little worms lying 

 dead about the heads of the polyps, 1 was at first inclined to think 

 that they lived by some process of absorption. I have, however, 

 since had ocular demonstration of their powers of deglutition. I 

 saw a polyp swallow a rotifer which was quite as large in diameter 

 as itself. How the rotifer was caught I did not see, as it was done 

 at a moment when my eye was away from the microscope. From 



* Since writing these remarks I have found an intermediate stage, where 

 one member of a trifid form was developing a fourth polyp, in the form of 

 a bud, near the base of that particular member. This bud consisted simply 

 of what I would term a perfect head, projecting beyond and clear of the 

 body of the parent. The body of the new polyp would doubtless be 

 developed in due course. 



