THE SPONGES. 125 



means simple, but may be regarded as composed of numerous erect lobes, 

 many of which are flattened, while others approach the cylindrical shape. 

 The lobes are intimately connected below, becoming more free and pro- 

 jecting above. Many of them appear, moreover, as buttresses projecting 

 from and only partially free from the faces, both inner and outer, of the 

 general lamella. The result of this complex order of growth is that the 

 underlying lamellate character of the body is made less distinct, the sponge 

 appearing at first sight as a fruticose mass. The whole mass in the natural 

 position is 110 mm. wide, with a greatest height of 170 mm,; the thickness 

 of the constituent lobes varying, but in the neighborhood of 12 mm. 



Numerous long conuli, covered with villi which are minute but distinct 

 to the eye, are present on the upper portions and projecting edges of the 

 lobes, nearly absent elsewhere. They are 3-6 mm. high, tapering to a 

 point, slenderly conical, or somewhat flattened and spatula-like. 



The dermal membrane appears to the eye as a fine reticulum, which 

 only indistinctly allows the arrangement of the internal cavities and paren- 

 chyma to- be seen. When cut across, the interior appears porous, with 

 very numerous small canals mostly 0.5 mm. or slightly over in diameter. 

 The color is a yellowish-gray. The sponge is very compressible and flexible, 

 yet firm and elastic. 



Oscula are scattered in some abundance over the upper ends and pro- 

 jecting edges of the lobes. They are rounded, 2-4 mm. in diameter, and 

 for the most part lead very quickly each into several efferent canals. Pores 

 rounded, 85-250 /x in diameter, in the meshes of the dermal reticulum ; 

 mostly one or two in each mesh. Interior of sponge is macerated, but in 

 places the size of the flagellated chambers can be made out; chambers 

 measuring 24 x 20 /x. 



Spicules. Oxea, smooth, slightly curved, cylindrical, not suddenly pointed 

 but tapering gradually at the ends (Figs. 3, 4, 5, Plate 17). The vari- 

 ability in the size of the spicule is considerable. Much the commonest 

 size is 85-90 /u, x 3-4 />(,. Longer and stouter spicules up to 100 /a x 5 ju, 

 are, however, not uncommon. Smaller slender forms 60-85 fx. x 2 jx are 

 found in the fibres and also scattered sparsely in the meshes of the skeletal 

 reticulum, perhaps representing stages in the development of the larger 

 spicules. Often the spicules in a particular fibre are of nearly the same 

 size, thus in one fibre measuring mostly 85 ju, x 4 /u,, in another fibre mostly 

 85 /x X 2 /x. 



