﻿MONTIPOEA. 13 



which the porous walls of the daughters project in tiers, the parent polyp continuing to grow 

 in height, and perhaps somewhat in size, while the daughters remain smaller and less highly 

 developed. 



In Turhinaria, the parent polyp shot Tip, but was soon smothered by the thick skeletal 

 walls of its ring of daughters which grew out around it, as an axis, forming a disc or cup. 



In Astrccopora, the wall became specialised by the outer edges of the costse forming long 

 protective echinulaj ; the budding took place laterally but without any definite order, so that 

 representatives of this genus are typically massive formations. 



In Montipora, the wall thickened at the expense of the polyp cavity, which thus remains 

 at a very low stage of development. The laminate character of the septa and costcC was 

 generally lost, and the wall became a plastic reticulum, in striking contrast to its rigid 

 development in Astrceopora. The budding of these very small but thick -walled polyps 

 leads to the formation of stocks chiefly distinguished by the abundance and richness of 

 their coenenchyma. 



The close relationship of Anacropora to Montipora will be discussed in the next section. 

 The summary of the conclusions arrived at may be briefly anticipated : — While Mon- 

 tipora and Anacropora are closely united into a subfamily, the Montiporinae, as already 

 proposed by Eidley, the remaining three genera, Madrepora, Turlinaria, and Astrceopora may 

 also be united, by the common possession of protuberant calicles, into the subfamily 

 Madreporinse. The family Madreporidte, as at present limited, contains these two subfamilies, 

 the Madreporinag, consisting of three genera, and the Montiporinse, consisting of two genera.* 



V. DIAGNOSIS OF THE GENUS. 



Montiporae, therefore, are Madreporidse, in which the primitive lamellate septa and costae 

 of the walls of the individual polyps have melted down with their synapticular junctions, 

 into a plastic reticulum. The coenenchyma resulting from the fusion of the walls is richly 

 and variously developed, especially for the formation of protective papillfe, tubercles, and 

 ridges. The polyps are correspondingly small and feebly developed. The tentacles (twelve 

 in number) are little more than papilla, and the septal skeletal apparatus consists chiefly of 

 vertical rows of spines present in two cycles, the second of which is typically rudimentary. 



VI. GEOGRAPHICAL DISTRIBUTION. 



The representatives of the genus Montipora, which deserve to rank high as reef-builders, 

 extend from the Red Sea throughout the whole Indo-Pacific region as far north as the Loochoo 

 Islands, China Seas, and southwards to the Barrier Eeef ; a single type {M. fragosa Verr.) 

 has been recorded, with, however, a note of interrogation, as far east as the Gulf of California. 



* These relationships will be found more fully discussed and illustrated in the Annals and Mag. 

 Nat. Hist, XX. (1897) p. 117. 



