﻿MONTIPORA. 11 



formed by this rampart of tubercles. But that the polyps can move up higher within 

 these pits is also certain from the occasional appearance of true septal spines projecting 

 irregularly from the inner faces of the tubercles. 



The Budding. — The budding in Montvpora takes place at the growing edges of explanate 

 forms, or in the tips of the branches in ramose forms, the young appearing in the middle 

 streaming reticulum wliich alone comes to the surface at these places. In massive forms 

 the young appear anywhere where there is room between existing calicles. A radial section of 

 an explanate Montiporan has a certain resemblance to that of a Turbinarian. But in Monti2}ora 

 the polyps developing on the growing edge not only bend upwards as in Turhinaria, but also, 

 if there is no epitheca accompanying the growing edge, downwards, which is not typically the 

 case in Turhinaria. Starting, then, from a young colony with a parent polyp and its ring of 

 daughters ranged radially in the saucer-like epitheca, these latter in lengthening give off buds 

 in the direction of the growth of the colony, which may bend upwards or downwards. Those 

 which bend downwards are generally sooner or later covered over by the advancing epitheca. 

 If the corallum thickens greatly so as to be massive fresh buds appear between the existing 

 calicles. We may again, then, say of Montipora what was said of Astrceopora, that the budding 

 appears to be indefinite and free, i.e. no such regular order is apparent as can be postulated for 

 Madrepora and Turiinaria. 



In this connection, the fundamental difference claimed by Kidley (op. cit.) between the 

 Madreporinte and the Montiporinse, viz. that the former bud centrifugally and the latter 

 centripetally, deserves comment. A wider survey than was then possible shows it to be too 

 limited a distinction to be of any use. The budding in all the Madreporidee takes place 

 laterally out of the porous walls of the polyps. It is only in the genus Madrepora that cer- 

 tain larger polyps shoot upwards and show what Eidley called the centrifugal method of 

 budding. On the other hand, the budding round the edge of the cup of a Turbinarian is in 

 every essential like that round the edge of an explanate or foliate Montipora, viz. from the 

 outer walls of the last formed polyps. 



IV. AFFINITIES OF THE GENUS. 



As above noted, the position assigned to this genus has oscillated between two families. 

 Dana (op. cit.) suggested that Montip)ora might be deduced from Madrepora by the degenera- 

 tion of th6 protuberant calicles, while Milne-Edwards * thought that they were Poritidffi 

 characterised by special abundance of the ccenenchyma. 



Taking this latter suggestion first, we find that the reason assigned for it is the 

 " trabecular " structure of the corallum and chiefly of the septa. These, it is contended, leave 

 no doubt as to the true affinity of the genus, in spite of its having certain form relations 

 (" quelques rapports de forme ") with Madrepora. 



Ann. Sci, Nat., (3) xvi. (1851) p. 54. 



