2 MADREPOEARIA. 



the buds appear, they form a definite ring around their parent, some way above the surface of 

 attachment. This ring of buds then itself buds again, and always in such a way that the 

 parent polyp forms a stalk, while the successive generations of daughters around it form an 

 expanded cup or plate on the top of it. The epithecal floor on wliich the parent polyp arose, 

 and which, 1 am convinced, plays an important part in the formation of coral skeletons, in 

 tlais case drops out ; the whole cup is built up entirely of the septa and their synapticular 

 connections. This young cup or plate, always budding round its edge, may eitlier, as will be 

 more minutely described in the following pages, continue the cup form, or sooner or later 

 lose it beyond all further recognition by the foldmg and frilling of the edges. 



The recognition of this peculiar method of growth of the genus Tiirbinaria removes it 

 from close kinship with any other genus of Stony Coral. Its probable relationship to the 

 genus Ifadrejjora will, however, be briefly indicated in the following pages. 



At the end of the volume will be found thirty plates (coUotyped reproductions of 

 pliotographs), revealing some of the more important methods of growth of Turhinaria and 

 Astrwopora, and, in a few cases, series showing the development of Turbinarians from their 

 initial cups. In preparing the original photographs of the specimens I have been greatly 

 indebted to the industry and technical skill of Mr. Eichards, attendant in the Zoological 

 Department, to whom my best thanks are due, and are here cordially tendered. The collotype 

 plates are followed by three plates, giving enlarged lithogi-aphed drawings, to show, in surface 

 view, the finer structure of the skeleton immediately surrounding the polyp cavities. 



The work of classifying the specimens, at aU times arduous, but especially so in the case 

 of such a higlily variable group as the Corals, has been throughout materially lightened for me 

 by the sympathy and encouragement which I invariably received from the late Keeper of the 

 Zoological Department, Dr. Gijnther, under whose auspices I first undertook to describe tlie 

 rich and ever-growing collections in the Museum, of which it is hardly an exaggeration to say 

 that the greater part are practically new to science. I take tliis opportunity of recording the 

 debt of gratitude which I owe to Dr. Gijnther. My sincerest thanks are also due to I'rofessor 

 Jeffrey Bell, not only for the great pains he has taken in editing my MS., but also for many 

 very valuable hints and suggestions as to the treatment of the subject. He has, also, at aU 

 times generously accorded me all the assistance in his power in the section of the Museum 

 of which he has more immediate oversirrht. 



HISTORICAL. 



The name Turhinaria was given by Oken,* in 1815, to the third genus of his 

 Gypskorallen. His somewhat quaint description is of very limited ajjplication, and must 

 have been suggested by small specimens ; indeed, he gives the size from " handgross bis 1'." 

 The corallum consists, according to Oken, of tubes brandling out from a common stem, like 



* ' Lehrbuch der Naturgeschichte,' Zool. i. p. 65. 



