49 



On a New Species of Cactogorgia. By Jas. J. Simpson, M.A., 

 B.Sc, Caruegie Research Fellow, Natural History Dc-ijartment, 

 University of Aberdeen. (With One Plate.) 



(MS. received January 24, 1910. Read January 24, 1910.) 



AmoN"GST the unnamed Alcyonaria in the collection of the Royal Scottish 

 Museum, Edinbui-gli. is a beautiful colonj* belonging to the genus Cacto- 

 gorgia, whicli 31r Eagle Clarke has kindly handed me for identification and 

 description. 



In 1907 {Trans. Roy. Soc. Edin.) I established the genus Cactogorgia 

 for several small colonies from the Indian Ocean, and referred these to three 

 separate species, viz. celosioicles, alciformis, and expansa. Thomson and 

 M'Kinnon, in Trans. Linn. Soc. (ZooL), 1909, have described another species 

 from the Seychelles under the name of Cactogorgia lamjxis, and the 

 present colony must also be referred to a new species. This we propose to 

 name Cactogorgia agariciformis, n. sp., on account of its ver}^ definite 

 mushroom-shape. 



It is interesting to note that the inclusion of these two new species has 

 not necessitated anj- change in the original generic diagnosis. 



Cactogorgia agaricifomiis, n. sp. 



This species is represented by a single specimen of a slightly orange- 

 yellow colour — that is, after prolonged preservation in alcohol. It has been 

 attached to rock, and the basal disc is overgrown by an encrusting sponge. 

 The colonj' (fig. 1) is 75 cm. in height, and consists of two very distinct 

 parts: (1) a lower, almost cylindrical, stalk, 4-8 cm. long, 7 mm. in diameter 

 at the base and 12 nun. at the top ; and (2) an upper, polj-p-bearing, part, 

 elevated in the centre, circular in outline and expanded horizontal!}', giving 

 the whole colon}- a very distinct mushroom appearance. The breadth of 

 the capitulum is 31 mm., and its maximum height 12 mm. 



The whole colony is very stiff and rigid, owing to tlie densely interlaced, 

 lar<^e, warty spindles, which are quite visible to the naked e3'e. These are 

 arran<Ted for the most part longitudinally, and give the translucent appear- 

 ance which was characteristic of C. celosioicles to the whole colony. 



The stalk contains several large canals (fig. 2). These are supported by 



