NOTE ON SAECODICTYON. 167 



since that by Milne-Edwards and Haime, as having the 

 polypes non-retractile, while S. catenata has eminently 

 retractile polypes. 



There remains then the question, ought our species to 

 be included in Glavularia ? If it cannot be separated 

 from the species of that genus, Glavularia as a name has 

 priority, having been established by Quoy and Gaimard in 

 1834 while Sarcodictyon catenata was not discovered by 

 Forbes till 1845 and was not described till 1847. I am of 

 opinion, however, that the constitution of the polype wall 

 out of two very distinct parts, a lower thicker opaque 

 coloured part into which the upper thinner translucent 

 colourless part can be retracted, is so different from the 

 condition seen in the species of Glavularia (see Hickson's 

 beautiful plates, which show, in all the species figured, 

 the body-wall extending in an unmodified state up to the 

 bases of the tentacles) that it gives us sufficient grounds 

 for the separation of S. catenata generically. And although 

 the character of the body- wall above referred to was not 

 included in the original description of Sarcodictyon, still 

 the species S. catenata, Forbes, was the type of that 

 genus and consequently Sarcodictyon is the name that 

 ought to be retained as the generic title. 



As to the further question whether there are any other 

 species of Sarcodictyon, that is a very doubtful matter. 

 Hickson mentions two species in all, — the well-known 

 S. catenata, and another "S. colinabum" which I have 

 never heard of. He gives as the locality Scotland, and 

 as authority " Forbes (?)," but I cannot find the name in 

 Forbes' works, and am inclined to think there must be 

 some mistake about it.* Hickson does not include in his 

 list of the species he desires to add to Glavularia, Sarco- 



* Since the above was printed I have heard from Prof. Hickson that he 

 possibly mistook a note book entry of S. agyloinerata for "8. colinabwm." 



