with descriptions of new Species. 183 



becoming somewhat ovoid and pointed above. Three or four 

 tentacles also sprout from it, while the horny polypidom forms 

 round the lower part, crenated or ringed, as it always is towards 

 the base of the polype-bearing bi'anches. When the stem has 

 reached a certain height, it swells out into small protuberances 

 here and there, which soon develope themselves into fresh 

 polypes. 



I have seen a planula apply one end of its body to the bottom 

 of the watch-glass in which it was kept, and then revolve on its 

 axis for a minute or two ; and no doubt it is in this way that 

 attachment is effected. 



Besides the vesicles in which the planula are produced, other 

 bodies occur at times on the Cordylophora in considerable 

 numbers, which call for some notice. These are elongate, and 

 often pointed at the apex, opaque white and of varying figure 

 (Plate VI. fig. 2). They spring from the branches and are sup- 

 ported on short stalks. They consist of an opaque mass of gra- 

 nular matter, surrounded by a delicate and perfectly transparent 

 corneous envelope, and are developed into polypes. I have seen 

 rudimentary tentacles sprouting from them, but have not watched 

 the course of development. These buds were present in great 

 numbers along with the vesicles, but disappeared as the season 

 advanced. 



Though much attenuated, there can be little doubt that the 

 corneous skin encloses the body of the fully-developed polype. 



It will be at once evident that Cordylophora presents us with 

 a somewhat strange assemblage of characters. Its embryology, 

 as now determined, separates it from the Tubularina with which 

 it has hitherto been associated. It has no tentacular ovisacs, 

 and its planula resembles that of the Sertulariadce. 



Its extensible, muscular and roughened arm is that of a Hydra 

 rather than a Tubularian. Its naked polype and the arrange- 

 ment of its tentacula are points of difference between it and the 

 Sertulariadce, while its vascular system (whatever be its precise 

 natui'e) is perhaps unique. Nor must we omit to note its well- 

 defined digestive cavity. In external character it is for the most 

 part a Tubularian zoophyte ; in embryology it is rather a Sertu- 

 larian, and there would seem to be points in which it differs 

 from both (Plate VI. figs. 1, 2). 



Additional Note on Cordylophora. — On one occasion, in remo- 

 ving a piece of the Cordylophora from one glass to another, a 

 polype-head was accidentally detached. In a short time the 

 wound caused in it by the separation had healed, and the base 

 had assumed somewhat of a bulbous form. In this free condi- 

 tion the detached head continued for (I think) a day or two. 

 At the end of that time I found that it had attached itself to 

 the watch-glass, and soon after a new branch began to shoot 



