154 PEECT SLADEN TEUST EXPEDITION. 



Genus ACIS. 



28. Acis solitaria, Pouitales. (Plate 6. fig. 7.) 

 Eor description see : — 



Pourtales: Bull. Mus. Conip. Zool. Harvard, 1868, p. 132. 



A dirty-white colony, consisting of two unbrancbed vertical stems and several other 

 uubranched pieces of the same appearance, may be provisionally referred to Acis solitaria , 

 Pourtales, of which the following description has been given : — " Corallum never 

 branching, five or six inches long. Coenenchyma thick, covered with large, elongated, 

 fiat spicules, which become smaller and converging on the not very prominent verrucie. 

 Polyps in two rows, rarely closely set ; a few scattering ones out of line. No longitudinal 

 furrow. Colour whitish. Locality, Gulf Stream, 200 fathoms." 



In the best specimen the two stems, which are united in a basal piece, rise to heights 

 of 18 cm. and 6 cm., and have a tliickness of 2-5-3 mm. The low verrucfe are scattered 

 all round. The axis is relatively thick, with a basal diameter of about 2 mm. One of 

 the other specimens reaches a height of 32 cm. 



The spicules include a superficial layer of large, thick, irregularly quadrangular 

 spicules, below which there are small warty sjnndles and irregularly shaped discs, 

 divaricate at the margins or at one end. The following measurements were taken of 

 length and breadth in millimetres : 1-5 X 0-7, 0-88 xOCl, 04.9X0-16, 0-26x0-07. 



Locality. Salomon, 60-120 fms. 



Previously recorded from Gulf Stream, 200 fms. 



29. Acis in die a, Thomson and Henderson. (Plate 8. fig. 3.) 

 For description see : — 



Thomson and Ilenclerson : Ceylon Pearl Oyster Report, No. .\x. 1905, pp. 297-298, pi. 2. fig. 3, 

 pi. 5. fig. 7, pi. 10. fig. 10. 



The well-defined operculum consists of a crown and points. The crown is three 

 spicules deep ; each point consists of two elongated hockey-club-like spicules. The 

 colour is typically greyish brown. 



Locality, Salomon, 75 fms. 



A small pink colony was also got, along with other grey colonies. 



Jjocality. Salomon, 60-120 fms. 



Previously recorded from Galle [Thomson and Henderson, 1905). 



30. Acis ceylonensis, Thomson and Hendei'son. 

 Por description see :— 



Thomson and Henderson : Ceylon Pearl Oyster Report, No. xx. 1905, pp. 299, 300, i^l. 6. fig. 3. 

 Some fragmentary colonies resemble this species in every respect. 

 Locality. Providence (D 4), 50-78 fms. 

 Previously recorded from Galle [Thomson and Henderson, 1905). 



