﻿148 MADEEPOEARIA. 



smooth system of plates separated by deep gyrating fissures ; above this surface the tips of the 

 threads just appear as low tubercles. The tubercles are bushy but have fairly sharp out- 

 lines to the naked eye. Here and there they fuse together to form tall, thin, flat and toothed 

 plates which, when the calicles are crowded, may form a delicate raised tracery surrounding 

 the apertures as direct continuations of their walls. Towards the growing edge, where the 

 calicles slope outwards, similar plates, developed out of the streaming layer, are found in all 

 stages of development, forming angular hoods over the raised edges of the aperture. Wliere 

 plates are formed, tubercles appear irregularly in the interstitial spaces. Only in the 

 tliickest parts of the corallum does the section show the formation of trabeculse. 



The sole specimen is a fragment which appears to have grown out from the side of some 

 object as a few lobate upwardly curving fronds with deep incisions between ; the fronds, 

 though joined below, overlap one another. While the earlier produced fronds appear to die 

 down, becoming the receptacle for sedimeut, the outer edge produces fresh fronds. From this 

 living edge, the coral grows backwards again over the sediment. Three different layers of 

 growth can be seen in the thickest parts with sediment between them, and further fresh 

 sediment has fallen upon and been partly incorporated iu the uppermost layer. The rising of 

 the ccenenchyraa to cover over the sediment suggests that this may be the stimulus for the 

 formation of the tall knobs and processes. 



It is obvious that while this is to all appearances the correct exi)lanation of the growth 

 of this individual specimen, the element of accident is too largely involved for it to be safe to 

 regard it as a good species. Lateral growths by means of distinct lobate fronds may, however, 

 well be regarded as typical. 



a. Palm Island, Great Barrier Eeef. Coll. Saville-Kent. (Type.) 



124- Montipara traheculata. (PL XXVII. fig. 2 ; PI. XXXIV. fig. 9.) 



Bescrvptien, — Corallum sends up compact ridges or tufts of nodulated processes, with 

 level tops ending nearly in the same horizontal plane ; dies away below, the living zone 

 being some 8 cm. deep. The lower edges, creeping down over the old stock, may turn 

 outwards to form short, thick, horizontal, free, tongue-like processes. 



The calicles in the lower parts of the colony are very small (0 • 3 mm.), inconspicuous 

 and scattered. They increase to double that size in the upper portions ; here they are deep, 

 with six well-developed primaries and frequently small secondaries; with the exception 

 of the two directives the septa are thin and delicate, and hence leave the aperture fairly 

 open and conspicuous. 



Ccenenchyma. While the typical reticular layer is present at the encrusting edges, 

 it is but very feebly and irregularly developed in sections of branching processes, the whole 

 section being trabecular without the usual axial strand. The irregular portions of the 

 trabeculse fill up the centre, while the more regularly radiating portions form the cortex. 



