THE STRUCTURE OE POEITES. 499 



Daua thought that there were no foliate forms, the nearest being 

 the sublamellate growths due to the fusion of the branches. 

 There are, however, a few thin e'xplanate forms which approach 

 the foliate condition. But there is certainly no rich foliation 

 such as we find in the foliate group of the Turhinarice and, only 

 in lesser degree, in the Montipores. 



The various growth-forms pass so gradually into each other 

 that it is only possible to group them in series. I place the ex- 

 planate forms, which admit of being described separately, as the 

 first division. The second consists of those explanate and en- 

 crusting forms which throw up lobes and columns ; these vary 

 imperceptibly in two directions : (a) into columns, and {h) into 

 branching forms, both without encrusting bases. The third group 

 consists of glomerate forms beginning («) with those with edges 

 expanding while the centre thickens, and may either, by con- 

 tinuous growth or by fresh relays, form great hemispherical 

 masses, and ending (h) with those in which the stock develops at 

 once as a rounded mass. These again are often difficult to 

 distinguish from one another : and hard and fast distinctions are 

 impossible. 



Some 'Preliminary Notes on the Soft Farts. 



In the diagram of Porites which I sketched in my former 

 paper*, in order to compare the structure of the skeleton upon 

 its flattened epitheca with that of a Madreporid, the porous septa 

 were purposely drawn very low- The diagram represents only 

 an ideal parent calicle of a Porites. As a matter of fact, while, 

 in very many forms, the calicle-depression is like that there shown, 

 the underlying reticular skeleton occupied by the soft tissues is 

 very much deeper. 



In sections of dried Porites, the staining of the living tissues 

 penetrates some 3-4 mm. beneath the surface, and, if a piece be 

 decalcified, the soft parts are left as a fleshy reticulum of nearly 

 even thickness (3-4 mm.), from the surface of which the polyps 

 project. The enteric cavities of the compound stock are simply 

 a network of fine canals. 



On decalcifying a fragment of P. recta (?) from Jamaica, 

 beneath the fleshy rind was found a cloudy mass of hyphse, 

 threads of which had run up through the skeletal reticulum into 



* This vol., p. 135, fig. 1. 



