﻿TUBEECULATE MONTIPORyE. 155 



growths, and the septa start from the inner faces of the tubercles. Between these taller clusters 

 of tubercles, the surface consists of the feathered tops of the trabeculse, loosely bound together, 

 while in deep depressions, rapidly filling up with ccenenchyma, the surface is an undifferen- 

 tiated loose reticulum, densely crowded with conspicuous but quite regular calicles. 



On the under surface the trabeculse form a mosaic of broad but irregularly shaped 

 plates, separated by deep fissures ; each solid plate may perhaps be composed of two or three 

 fused trabecule, its surface being marked by groups of fine white points. These thickened 

 trabeculse, forming a raised wall round the calicles, give rise to the thick solid septa. 



There is only one specimen of this beautiful coral, which is characterised as well by the 

 spike-like protrusions of the streaming layer as by the clumps of tubercles which raise the 

 calicles above the surface. In this latter feature we find an explanation of the prolific 

 formation of erect processes. In this respect it resembles specimen e of M. solanderi which 

 is also dish-like and forms great numbers of erect processes. The fact that this particular 

 specimen of M. solanderi appears to be only a special method of growth of that type, leads one 

 to suspect that M. striata may be but another form of M. australiensis from the same locality. 

 The striate edges and the knobbed septa are features which they have in common. There is no 

 reason why these two may not be closely related ; until, however, we have the direct evidence 

 of transitional forms, it is better to describe them separately. The colours of this coral are 

 very beautiful. The spikes and growing edges are suffused with rose-pink, while the sides 

 of the processes are olive-green, against which the white tubercles stand out in contrast. 



a. Houtman's Abrolhos. CoU. SavUle-Kent. (Type.) 



130. Montipora circinata.* 



Description. — Corallum forms a single conically twisted frond, rising from a narrow band- 

 like base ; the edges curl round spirally and overlap but do not fuse ; 2 mm. thick at growing 

 edge and rapidly thickening to a centimetre or more near the base. 



The calicles are small, ■ 50 mm., conspicuous owing to the depth of the open fossa, 

 scattered, and for the most part confined to the depressions between the coenenchymatous 

 elevations ; the primaries are but slightly and irregularly developed, and there are only faint 

 traces of the secondaries. On the under surface, while many calicles are mere openings in the 

 level reticulum, others are walled round by uprisings of the ccenenchyma. The whole outer 

 surface is covered with irregular prominences 2 to 3 mm.^high, with calicles on or near 

 their tips. 



The ccenenchyma. A section through the base shows the compact middle reticular layer 

 and inner and outer compact trabecular layers ; while the outer layer is very compact and 

 more reticulate, the inner layer is composed of thick and not very closely packed trabecule. 



* This name is suggested by Mr. Saville-Kent in 'The Naturalist in Austraha,' 1897, p. 146, for 

 this coral, which is figured on the same page and also on pi. xxiv., upper figure. The coral is not, 

 however, described 



X 2 



