THE ANATOMY OF ALCTONIUM DIGITATUM. 353 



the British area^ namely A. digitatum and A. glomeratum 

 (PI. 36, figs. 1 and 2). The yellow variety of A. digi- 

 tatum referred to above cannot be separated as a distinct 

 species from the white variety. There are no features in the 

 mode of growth, character of the spicules, or general anatomy 

 which distinguish the two varieties, the only difference being 

 the yellowish tint in the spicules of the yellow one. 



Alcyonium glomeratum was first discovered by Hassall 

 in 1841^ and he referred it to Miiller's species Alcyonium 

 rubrura; but on being told by a Mr. Macgillivray that it 

 differed from A. rubrum, gave it the name Alcyonidium 

 glomeratum (14). (Throughout his descriptions Hassall uses 

 the word Alcyonidium in place of Alcyonium.) The species is 

 defined as follows — " Polypidoms massive, of no very definite 

 outline; colour a deep uniform red, the shade of which ap- 

 proaches to vermilion." 



In the second edition of Johnston's ' Zoophytes,' vol. i, 

 p. 178, there is a long quotation from Couch on A. glomera- 

 tum, who says, ^'The colour externally is of a deep blood- 

 colour, and internally is but slightly lighter. The lobes are 

 very numerous, and divide nearly as low down as the base. 

 The spicula are numerous and irregularly arranged; they are 

 linear, elongate, pointed at both extremities, with uneven or 

 granular spaces between; sometimes they are simple, and at 

 others united into K-shaped bodies, and occasionally wanting 

 one or other of its members, forming an imperfect K. 



When Gray examined the species in 1865 (12) he made it 

 into a new genus, giving it the name Uhodophy ton Couchii. 

 The description of the genus is as follows: — ''Coral flesh 

 cellular, covered with a hard calcareous coat, contracted at the 

 base, expanded above, and divided into several oblong lobes or 

 branches, covered with short cylindrical tubes with a circular 

 mouth. Polyps half retractile, forming when contracted a 

 white tubular termination to the cells. The more developed 

 cells of the polyps, especially those at the end of the lobes, 

 are longitudinally grooved." 



''This genus," he continues, "differs from the typical 



