7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 31 



epitheca are conspicuous in most colonies. The primitive calicle was low and 

 thick, the fossa shallow, the septa fused and the columellar tangle conspicuous 

 in the floor of the fossa and from it a rosette of 6 paliform knobs arose. 

 This primitive type of calicle was supposed, on account of this rosette, to 

 distinguish the genus Rh., but it reappears on the free edges of colonies no 

 matter how specialised the calicle structures typical of those colonies may be, 

 so that all massive Goniopores are Rhodarseas at the sides. The primitive 

 calicle had 24 septa which still persist in most modern representatives of the 

 genus, at any rate in the calicles on the free edge. The normal symmetrical 

 budding of a parent calicle such as is described above could only result in 

 the formation of circular slightly convex astrseiform colonies. This, the simplest 

 and most primitive growth form, is exemplified by several fossil and recent 

 species, and all other known species may be deduced from it. There are two 

 clear lines of departure from this primitive form, (1) some have become less convex, 

 growth has gone on round the edges and the colony has become flattened (or 

 explanate), (2) some have become more convex and the colonies have become 

 hemispherical and columnar. In the explanate colonies the primitive type of 

 calicle either persists or the skeleton of the calicle becomes flattened down by 

 reduction of the skeletal elements into short, thick, vertical trabeculse; the 

 colonies in this case become thin and the calicles obsolete. In the other line 

 of development, towards the formation of columnar stocks, the walls of the 

 calicles in the centre of the colony grow in height, and according to the 

 variations in speed and uniformity of this central growth there appear all the 

 known modifications of the massive type. The polyps of the central region 

 rise in lengthening calicles and secrete a tabular floor and from this new level 

 they usually throw out a new edge which covers up and kills the backward 

 polyps round the original edge. The epitheca under the new edge is continuous 

 with the tabular floor. Such a process results in massive forms. The central 

 growth is continuous upwards through the stock, but there is a succession of 

 edges, one covering the other and each with its supporting and often over- 

 lapping epitheca. Whatever be the specialisation of the deep central calicles 

 those on the free edges remain more like the primitive low-walled type. 

 The author then deals with the secondary modifications of the explanate growth 

 and with variations on the massive growth-form. Goniopora is more primitive 

 than Forties and it seems probable that the Poritidse and Madreporidse had a 

 common origin from the simpler Eupsammiids. A full diagnosis of G. is given. 

 A summary of the records suggests that the genus arose in the Lower Creta- 

 ceous of the Crimea and then spread over southern and western Europe and 

 through Egypt and Persia into the Indo-Pacific region where alone it survives. 

 The majority of the known extinct species range from the Lower to the Upper 

 Eocene when the genus flourished in the seas of southern Europe. Through 

 the Miocene it dwindles away. About 150 modifications of what was probably 

 the primitive type are described and many of them figured so as to show the 

 method of growth and structure of the calicle. The specimens are arranged 

 by the use of geographical symbols. 



Duerdenf 1 ) finds that in Siderastr&a radians the 6 members of the first cycle 

 of septa appear simultaneously, shortly after fixation of the larva, within the 

 entocoels of the first cycle of mesenteries. 6 members of a second cycle (the 

 temporary predecessors of a later permanent cycle) are shortly afterwards formed 

 within the primary exoccels, they later become bifurcated peripherally. The 

 6 members of the permanent second cycle of entosepta arise in dorso-ventral 

 succession within the entocoels of the second cycle mesenteries soon after these 



