28 Coelenterata. 



forms having been produced by budding, the evolution of the polyp in the 

 Antipatharia went no further and hence the primitive form and structure are 

 to a large extent retained. The succeeding forms diverged somewhat in two 

 directions, one more complex with 6 accessory mesenteries leading to Leiop., 

 the other simpler with only 4 accessory mesenteries giving rise to the remaining 

 genera of which Schizopathes is the most highly differentiated. 



Bernard (^ gives a diagnosis of the genus Porites, in which he merges 

 Synarcea (which shows no fundamental distinction), Neoporites and Cosmoporites 

 which fall within the range of ordinary variations, Stylarcea which was founded 

 on young colonies of immature individuals, and Napopora which is clearly 

 a P. The morphology of the skeleton is discussed in detail especially in 

 regard to the theca, septa, pali and columellar tangle. In Madreporidse (with 

 the exception of Montipora} the theca typically rises as cups above the level 

 of the intervening tissue, but in Poritidse there is no known case of this oc- 

 curring,, the intervening costal tissue is always either level with the thecse or 

 may often rise above their apertures. Among the Madreporidre this latter 

 condition is found only in Montipora. The wall of the theca in P. may be 

 thickened by the intervention of tissue between the calicles and by incipient 

 synapticula? becoming complete and forming an inner wall. Goniopora possesses 

 three cycles of septa, while P. has only two. Summaries of the geographical 

 distribution and of the distribution of the various growth forms and types of 

 calicle are given. 256 forms are described, arranged in 6 geographical groups, 

 Polynesia, Australia, Malay Region, Indian Ocean, India and Persia, Red Sea 

 and Egypt. 



According to Bernard ( 2 ) the West Indian forms of Porites are distinguished 

 from the Indo-Pacific forms by (1) their stiffness or want of plasticity, (2) an 

 almost complete absence of any form which can be called coenenchymatous, (3) 

 a boldness and irregularity in the arrangement of the calicle skeletons very 

 different to the delicacy and symmetry of the smaller calicles of Indo-Pacific 

 forms. The differences depend on the fact that the trabecular, horizontal and 

 synapticular elements which compose the skeleton are thicker and coarser in 

 the Atlantic and West Indian forms. Probably the forms from the Red Sea 

 will also prove to have special characters dividing them from the other Indo- 

 Pacific forms, facts in support of the author's scheme of geographical classi- 

 fication. While Goniopora first appeared in the lower Cretaceous of the Crimea 

 and had its maximum development in the middle Tertiaries, it is possible that 

 P., as a derivative of (?., is attaining its maximum in modern seas. The 

 discovery of a fossil G. in Jamaica seems to show that G. has passed its 

 maximum and has given place to P. In his account of the growth forms 

 the author concludes that the form assumed by the initial colony is always 

 endeavouring to repeat itself on every suitable surface of the resulting stock 

 so that each portion of a colony is a repetition, a little better or a little 

 worse nourished, of the initial or basal stem. The majority of forms branch 

 by dividing into two but there is a tendency to the abortion of one branch, 

 the one which survives is usually that nearer the vertical, and into it the vegetative 

 energies of the colony are concentrated thereby ensuring upward growth of 

 the stock. The aborted branch far out of the vertical is not in a position 

 favourable for the growth of the prong, treated as a new unit and trying to 

 repeat the initial or basal colony, hence its inability to grow. When foreign 

 objects come too near the surface of a colony and the natural functions of 

 the polyps are interfered with the walls tend to proliferate. Each stock produces 

 by gemmation its initial colony which assumes some characteristic shape, and 



