256 



"ENDEAVOUR" SCIENTIFIC RESULTS. 



The single specimen, preserxed in a dry state, is a small 

 sponge of indefinite shape growing dispersedly over the fronds 

 of a Toliaceous calcareous Bryozoan. It consists in part ot a 



thin spreading layer closely in- 

 p, vesting the surface of the fronds,, 



and in part of irregular com- 

 I pressed outgrowths arising 



along their margin s. The 

 lamellar portions of the sponge 

 (which constitute by far the 

 greater portion of its bulk) have 

 an uneven, irregularly undulat- 

 ing surface, and, owing to var}- 

 ing rates of growth at different 

 points, an irregularly lobed and 

 broken margin ; they xary from 

 I to 3 mm. in thickness, are 

 indefinite in width, and attain, in 

 the present instance, a maxi- 

 mum height of 50 mm. Owing 

 to incomplete coalescence be- 

 tween the marginal lobes as 

 growth proceeds, the lamellye 

 are frequently fenestrate. There 

 are no certain indications of 

 oscula. The surface is minutely 

 porous. The colour is yellowish- 

 grey ; the consistency firm, com- 

 pressible, slightly brittle ; the 

 texture, finelv fibrous. 



'\he main skeleton is a web- 

 likc sub-renieroid irregular re- 

 ticulation of pale slender horny 

 fibres with pauciserially or uni- 

 serially arranged axial spicules 

 (principal styli). The precise 

 formation of the skeleton is diffi- 

 cult of determination ; apparently 

 there is a primary reticulation 

 of stouter fibres, the meshes 

 of which are occupied by a 

 Principal styles, b Auxiliary secondary interreticulum of 

 stvle. c Chela, a Toxa. ^, ... 



mostly umspicular connecting 



fibres. The outlines of the 

 stouter fibres are \ague, and the arrangement of their spicules 

 is disorderly ; they seldom exceed 40 /i in diameter. The 

 (usually single) spicules forming the sides of the angular 

 meshes of the interreticulum are probably always surrounded^ 



Fig. 53 — O. cofiOaoostt. 



