THOMSON AND MACKINNON— STOLONIFEllA, ETC. 187 



The family iacludes the Ibllowing genera: — 



Siphonogorgia, KoUiker. 

 Chironephthya, Wriglit and Studer. 

 Paranephthya, Wright and Studer. 

 Sclevuiiephlhya, Wriglit and Studer. 

 Stereacanthia, Thomson and Henderson. 

 Agarlcoides, Simpson. 

 Cactogorgia, Simpson. 



Numerous attempts have been made to find satisfactory distinctions between the first 

 two genera, but wo are compelled to agree with Ktikenthal that none holds good. 

 That, at least, is our experience. The following table may serve to illustrate tlie 

 contrasts that liave been drawn : — 



ClIIKONEPHTHYA. 



1. Nephlhya-WVe iorm oi gvovith. (Hickson.) 

 3. Anthoeodia rarely completely retracted. 

 (Hickson.) 



3. Antliocodial points with four principal 



spicules arranged "en chevron." (Hick- 

 son.) 



4. One large main canal in stem. (Harrison.) 



SlPnONOCiORGIA. 



1. Gorgonid-like form of growth. (Hickson.) 

 3. Anthoeodia may be completely retracted. 

 (Hickson.) 



3. Anthoeodia with the spicules irregularly 

 placed, or arranged in a fan-like manner. 

 (Hickson.) 



4. Numerous, fairly eiiual-sized canals in 

 stem. (Harrison.) 



What we have found is, that a given specimen may be in some of its characters 

 Siphonogorgia-likQ, and in others Chironephthya-\\\Q. As an example of this we may 

 veiei io Siphonogorgia [Chironephthya) maorospiculata, Thomson and Henderson. The 

 specimens of this species in the present collection show a Gorgonid-like mode of 

 growth and numerous longitudinal canals in the stem [Siphonogorgia characters 

 according to Hickson and Harrison), but the anthocodial crowns have A-shaped points, 

 each composed of four converging pairs of spicules (one of the most striking characters 

 of a Chironephthya, according to Hickson). 



Genus SIPHONOGORGIA. 



53. Siphonogorgia variabilis (Hickson). (Plate 11. fig. 5.) 



= Chirovt'phthya variabilis, Hickson. 



Eor description see : — 



Hickson: Alcyonaria of the Maldives, pt. i. (1903), in Fauna and Geography of the Maldive and 

 Laccadive Archipelagoes, vol. ii. pt. i. p. 488, pi. 36. figs. 8, 9, 10. 



A large number of specimens, differing from one another in small details, may be 

 referred to this variable species. 



(A) One group from Providence (50 fms.) has the main stems and branches cream- 

 white, while the lesser branches are of a purplish-pink colour, with their tips and the 

 anthocodiaj deep purple. 



(B) Another haul from Providence (50 fms.) contains some extremely beautiful 

 specimens of a delicate pale pink colour, deepening into rose-pink on the branches and 

 lower portions of the stem. The most perfect colony is about 11'5 cm. in height, and of 



SKCOND SERIES.— ZOOLOGY, VOL. XIII. 25 



