183 Rev. T. Hincks on British Zoophytes, 



pliytes, by means of planulce (motive buds), wbich are matured 

 in deciduous vesicles. These are oval and are produced on the 

 polype-bearing branches. They consist of a thin corneous en- 

 velope with a soft mucous lining of some thickness, enclosing a 

 central cavity in which the reproductive bodies are contained. 

 In an earlier stage of development, the interior is occupied by a 

 mass of granular matter surrounded by a delicate membrane. 

 At first the vesicle appears as a small transparent oval case, bud- 

 ding from the branch, into which an offshoot from the fleshy 

 axis of the polypidom has penetrated. Gradually it increases 

 in size, and after a while the contained mass is resolved into a 

 number of round bodies, which lie clustered together within the 

 membranous sac, a stump of the offshoot remaining at the 

 bottom of the vesicle. I have counted as many as twelve of 

 these bodies in a single capsule, but more commonly they 

 amounted to six or eight in number. For some time they un- 

 dergo apparently but little change, merely increasing in size. At 

 length however a marked alteration in form takes place. They 

 become first oval, then elongate, and are now prepared to issue 

 from the capsule as plcmul<s. This change occupies two or three 

 days. When on the point of escaping they are found clustering 

 together at the upper part of the vesicle. 



I was fortunate enough to witness the exodus of a whole com- 

 pany of these embryo Cordylophorce. As there is no natural 

 opening to the vesicle, as amongst the Sertularians, a passage 

 has to be made through the soft external covering. This was 

 effected by one of the planulce, which acted as a pioneer, and 

 slowly, and with some difficulty, as it seemed, worked its way 

 into the sun-ounding water. As soon as the leader had escaped 

 the others followed in succession, and with great ease and ra- 

 pidity, — with the exception of one, which happening to have the 

 portion of its body representing a head turned in the wrong 

 direction, moved towards the bottom of the vesicle instead of 

 towards the water, and was some time in finding the right road 

 and following its companions. 



On reaching the water the planula remains inactive for a few 

 seconds, undergoing remarkable changes of shape; the body 

 then acquires a rotatory motion, and it sails off with considerable 

 rapidity. It is elongate, and leech-like in form, somewhat 

 broader at one extremity than the other, white, opaque in the 

 centre, and semitransparent towards the edge of the body. 



The planulce made their escape late in the evening, and on the 

 following morning some of them had become attached. They 

 fix themselves by one exti-emity, which expands into a roundish 

 disc, the body itself standing erect in the centre of it. This 

 gradually assumes the form of the polype, the upper portion 



