THOMSON AND RUSSELL — AXIPEEA. 



161 



Family GorgOnidSB. 



Genus GORGONIA. 

 43. Gorgonia dubia, sp. n. 



A complete colony, lO'S cm. liigb, with an almost uniform diameter of 2'5 mm. 

 About 2-75 cm. above the slightly encrusting basal attachment the stem forks into two 

 simple branches ending bluntly. 



The axis is brown ; the coenenchyma is thin and of a cream-white colour. Verrucin 

 occur all over the stem and branches, irregularly and in spirals ; they are low, eight- 

 rayed, and wart-like : the polyps are completely retractile. The expanded polyps show 

 an armature of eight triangular points, each consisting of four to six pairs of delicate 

 spindles. 



The sjiicules of the coenenchyma form a close-set pavement ; they are very uniform — 

 for the most part small spindles with i-ather prominent tuberculate warts, which show a 

 strong tendency to be arranged in zones. The following measurements were taken of 

 length and breadth in millimetres : -221 X 034, -187 X '025, -153 X •031. 



Some of the spicules are stouter and shorter, approaching barrel-shape (-185 X ■068, 

 ■102x051 mm.). There is no trace of anything resembling the "scaphoid" spicules 

 described as characteristic of the genus Gorgonia. In this respect our species comes 

 nearest to Gorgonia oppositipinna, Eidley, and G. australiensis, Ridley, where tlie 

 spicules are mainly whorled spindles, the scaphoids being only slightly developed. It 

 differs from these species in the mode of branching, the arrangement of the polyps on 

 the branches, the colour, and the entire absence of scaphoid spicules. 



Locality. Amirante, 32 fms. 



Family GrorgonelMaB. 



The collection includes numerous specimens of elongated Gorgonellids belonging to 

 Scirpearella and related genera. 



We have provisionally named these, but the definitions of the genera are in a very 

 unsatisfactory state, and a revision of the family is urgently needed. Tliis has been 

 undertaken by Mr. James J. Simpson, B.Sc. 



Genus NICELLA. 



44. Nicella dichotoma. Gray. (Plate 7. figs. 1 & 5.) 



For description see : — 



Gray : Proc. Zool. Soc. 1859, p. 481 ; Catalogue of Llthophytes in the British Museum, 1870, 

 pp. 40, 41, 1 fig. 



Several colonies, of chestnut-brown to umber-brown colour. The largest is 20 cm. in 



