182 THE VOYAGE OF H.M.S. CHALLENGER. 



makes a new genus, Trinella, for a form wliicli on examination proves to be but one of 

 Verrill's species overgrown with a Palythoa and a Sponge, and establishes the family 

 Trinellidse for the two genera Trinella and Parisis. Verrill describes two species — 

 Parisis fruticosa from the Sulu Sea, and Parisis laxa from Hong Kong. 



The rough hispid surface mentioned by Verrill as characteristic of the outer layer of 

 the ccenenchyma is possibly due to the siliceous spicules of a Sjaonge, for we find in all 

 the specimens in the Challenger collection, when free from parasites, that the spicules 

 form a more or less tesselated pavement, which lies in an even layer over the whole of 

 the ccenenchyma and extends up to the edge of the verrucse. From the sclerogorgic 

 nature of the nodes and internodes when young, we place this genus here instead of 

 with the Isidse. 



This genus seems to approach Clathraria, Gray, in the form of the spicules. 



Parisis fruticosa, Verrill (PL XLI. fig. 2). 



Parisis fruticosa, Verrill, Bull. Mus. Comp. Zool., vol. i. p. 37, 1865. 



„ mauritiensis, Eidley, Ann. and Mag. Nat. Hist., ser. 5, vol. x. p. 131, 1882. 

 Trinella swinhoei. Gray, Cat. Litliophytes, p. 12, fig. 4. 



This interesting form — the type species of Verrill's genus — was clescrit)ed from a 

 specimen taken in the Sulu Sea. The diagnosis is as follows — " Large, flabelliform ; 

 the principal branches arising irregularly along the sides of the trunk, divide and 

 subdivide ra23idly into other smaller branches and branchlets, producing a densely 

 ramulous frond. The branches ascend and diverge usually at an angle of about 50° ; the 

 branchlets often spread at right angles, and do not coalesce. Papillae numerous, crowded 

 on the branchlets, elongated, conical. Colour grayish-yellow ; axis white ; internodes 

 yellowish-brown. " 



No measurements are given and the ccenenchyma and spicules are not described ; 

 still the species seems to us to be well represented by a form in the collection from the 

 Banda Sea which unfortunately exists only in fragments. 



The colony, of which the fragments would seem to represent two separate specimens, 

 are unattached. The largest measures about 130 mm. in height, with a basal diameter 

 of 3 "5 mm. It branches irregularly, but all the branches are in the one plane; many 

 of them aojain branchina;. There is no anastomosing of the branches. Owing to the 

 lateral arrangement of the poljqjs the branches have a flattened appearance. 



The axis consists of a series of hard calcareous internodes, of from 6 to 10 mm. in 

 length ; these are cylindrical, somewhat rough on their surfaces, and markedly grooved. 

 The nodal regions are in the spirit specimens about the same diameter as the internodes, 

 but are not more than from 0"5 to 1 mm. in length ; in these latter the sclerogorgic tissue 

 is but feebly calcareous, and it is seen on cross section to assume a radiate form ; on the 

 surface it is grooved, like that of the internodes. 



