﻿GLABKOUS MONTIPOR^. 33 



h. Rising in lobes or branches. 



16. Montipora obtusata. (PL XXXI. fig. 14.) 



Moniipora verrucosa, De Blainville, Man. d'Act. (1834) p. 388, and Atlas, pi. Ixi. figs. 1 and la (non 



Quoy and Gaimard). 

 Moniipora obtusata, Quelch, Ghall. Eep. Eeef Corals (1886) p. 174, pi. viii. figs. 3, 3a. 



Description. — Corallum horizontal, plate-like, thick but transmitting light ; the wavy- 

 round edges, 5 mm. thick, tend to bend up. All the free portions of the corallum supported 

 on the under surface by a well developed concentrically wrinkled epitheca. The upper 

 surface to the naked eye is smooth, but raised into thick, finger-shaped processes, which are 

 in all stages of development from mere hemispherical or conical mounds up to knob-like 

 excrescences 3 cm. high. These processes are irregularly scattered and tend to be taller near 

 the centre of the corallum ; here they may flow together to form irregtdar masses. The 

 processes tend to slope slightly away from the vertical axis of the corallum. They are, to 

 the naked eye, smooth and evenly studded with calicles like the rest of the upper surface of 

 the corallum. At each new period of growth, the corallum spreads over a previous smaller 

 growth, not always in close contact with it, but arching over it, supported on the raised 

 processes so that there may be a space between the explanate portions of the successive 

 coraUa. 



Calicles very minute, • 5 mm. in diameter, open on the smooth surface of the corallum, 

 at the tips of the processes hardly demonstrable ; evenly distributed, 1 • 5 to 2 mm. apart, over 

 the whole corallum, even round the growing edges and on the under surface where the latter 

 is not covered with epitheca. Septa distinct but irregular, reaching beyond the half radius 

 circle, and consisting of two cycles or parts of two cycles which are generally distinguishable 

 from one another. 



Ccenenchyma in section dense, with a thin, perfectly solid basal layer in contact with the 

 epitheca. The streaming reticular layer is dense and composed of thick glassy threads ; above 

 this occurs a fairly thick layer of closely packed, nodulated, more or less vertical threads 

 which hardly form distinct trabeculse. The surface'of the corallum is composed of flat, highly 

 perforated branching flakes, the pointed edges of which, grouped together in a plane round the 

 calicles, form the septa. This surface reticulum is close and solid on the lower level portions 

 of the coraUum, but light and open on the sides and slopes of the rising processes. At the 

 tips of the processes, the texture alters, owing to the elements of the streaming layer, which 

 here comes to the surface, projecting in all dii-ections. 



In establishing this species, Quelch appears not to have recognised that it is specifically 

 identical with the coral figured by de BlainviUe in the Atlas to his ' Manuel ' as the Porites 

 verrucosa of Lamarck. Although de BlainviUe had the advantage of examining Lamarck's 



