32 Proceedings of the Royal Physical Society. 



hood of Tarbert, Loch Fyne, I again met with Sarcodictyon 

 growing over stones and shells, but this time two. forms 

 occurred, one red and the other pale yellow. This circum- 

 stance induced me to examine the minute structure of 

 the two varieties with the view of determining whether or 

 not there is any essential difference between tliem, and on 

 returning to Liverpool I examined the specimens dredged at 

 Lamlash in 1880. 



All the colonies in my possession appear to belong to one 

 species, Sarcodictyon catenata (Forb.). Although this form 

 has been briefly described or referred to by several authors, 

 its anatomy and histology have never, I believe, been 

 thoroughly investigated. 



11. Historical. 



The species was first discovered and named by Professor 

 Edward Forbes, but I have not been able to find his original 

 description of it, if one was ever published. In Johnstone's 

 "History of British Zoophytes," 2d edition ^ (1847), the 

 generic and specific descriptions of Sarcodictyon catenata are 

 given on Forbes' authority, but without any reference to a 

 publication, while the few rough but characteristic figures of 

 the appearance of the colony are stated to be reproductions 

 of Forbes' drawings. From this it seems likely that Forbes 

 did not publish an account of Sarcodictyon previous to 1847, 

 but supplied Dr Johnstone with the descriptions and figures 

 found in the " British Zoophytes," 2d edition. In that work, 

 the species is rightly placed amongst the Alcyonaria, and the 

 description and figure are sufficient for identification, but no 

 account of the minute structure is given. 



In January and February 1851, Professor Edward Forbes 

 read before the Ptoyal Society of Edinburgh a paper ^ entitled 

 "On some remarkable Marine Invertebrata new to the 

 British Seas," in which he stated, that while on a yachting 



^ The genus Sarcodictyon is not mentioned in the 1st edit, (1838), and it 

 is not referred to in Mr William Thompson's " Report on the Fauna of 

 Ireland" (Brit. Assoc. Rep., 1843, p. 245), where all the known British 

 Alcyonaria are given upon Dr George Johnston's authority ; consequently 

 Forbes must have discovered it between 1843 and 1847. 



'Trans. Roy. Soc, Edinb., vol. xx., p. 307, 1853. 



