143 



GENUS CACTOGORGIA,' Simpson. Plate VII, figs. 1-9. 



Systeiiiatic Position. 



This new type belongs to the family NephthyicUv, and the exceptionally 

 dense spiculation of the canal walls indicates its position in the sub-family 

 Siphonogorgina? (Wright and Studer, "'Challenger' Reports, Zoology," vol. 

 xxxi., p. 189). In certain respects it shows affinities with the Cldronephthya- 

 Siplioiiogorgia type, but the following differences may be noted : — 



{a) The colony is much more densely spiculose, firm and rigid. 



(/>) There is a marked distinction into trunk and polyp-bearing portion. 



(c) There is no definite branching, but the polyps are borne mainly on the 

 margin of flattened lobes. 



Generic, Diagnosis. 



The colony is upright with a basal attachment, and resembles a Cactus in 

 its mode of growth; it consists of (1) a basal trunk, very rigid and densely 

 spiculose, in which several small cylindrical canals are imbedded ; and (2) an 

 upper polyp-bearing portion, which in some cases bears expanded lobes. There 

 is generally a flattening of the polyp-bearing part and lobes, and the polyps are 

 borne in several rows, for the most part along the margin. The anthocodite 

 are completely retractile within more or less prominent verrucre composed of 

 large spicules arranged longitudinally ; they are comparatively large and bear 

 a dense armature with a " crown and points " arrangement. The tentacles are 

 not retractile, but are simply infolded and overlap the oral region ; they are 

 covered on the aboral surface with numerous scale-like sclerites. The spicules 

 vary in type in the different parts ; those of the stem and trunk are thick 

 spindles covered with multi-tuberculate warts ; those of the anthocodiaj (" crown 

 and points ") are straight or curved spiny spindles or clubs ; those on the aboral 

 surface of the tentacles are small, fiat and scale-like. 



The specimens differ so much from one another that they seem to require 

 the definition of tliree new species, for wliich the following names are proposed : 

 Cactogirrgia cehmoides, from its resemblance to Celosia ; C. expansa, from its 

 flattened appearance ; C. alci/onnis, from its antler -like mode of growth. 



Speriflr. Diagnoses. 



C. celosioides, Simpson. 



The trunk and polyparium are much flattened, of a light brown colour, stiff 

 and rigid, with a translucent slieen. The coenenchyma is densely spiculose, 



^An account of this new genus and of its species was published separately. See .J.J. 

 Simpson, "On a new Siphonogorgid Genus Caotogorgia ; with descriptions of three new species". 

 "Trans. Eoy. Soc," Edinburgh, vol. slv. (1907), pp. 829-36, 1 pi. 



