﻿132 MADREPOEAEIA. 



at the growing edge ; 1*6 to 2 cm. thick near the centre of attachment. A white, chalky 

 epitheca develops about 10 cm. behind the growing edge. The under surface is covered with 

 drop-like processes of the ca3nenchyma, wavy, conical and pointed towards the growing edge. 



Calicles conspicuous, averaging less than 1 mm. across, clear, deep fossa opening in the 

 loose reticulum of the coenenchyma, but often sharply defined by single threads of coenenchyma, 

 crowded, two often in contact, septa with well defined primaries in regular series ; secondaries 

 often only partially represented. On the under surface calicles very sparse, generally 

 associated with one of the conical processes, opening sometimes at its tip,, sometimes on its 

 side or at its base. 



The coenenchyma, in section, shows a very thick layer of loose reticulum, streaming 

 towards the growing edge and occupjing the whole thickness of the corallum for 3 to 5 cm. 

 from the edge ; it is more than 5 mm. thick near the central attached region of the coral. 

 From tills perpendicular threads descend to form a rather dense layer resting on the epitheca 

 or else composing the smooth, stony but deeply fissured under surface. This surface is 

 beset with short granular points, round wliich the thin, white epithecal film first appears as 

 minute discs marked with concentric lines. The trabecular layer is very well developed, nearly 

 1 cm. deep at the thickest part, the trabecule being long, tapering, Ibosely grouped, of various 

 thicknesses, the cross junctions being, in comparison, very thin and light. The tubercles 

 are tall, thin, erect flames, sometimes like fine bundles of wavy hair. They thickly and evenly 

 cover the whole sui-face, being tallest and most conspicuous in the slight valleys or round the 

 depressed edges of the open slits. On the reflexed margins of these slits the reticulum is 

 not so loose or open, but is composed of liorizontal flakes, so that the corallum is here 

 opaque and white in contrast mth the blue-grey of the upper surface. The growing edges 

 of the reflexed margins are swollen into, a light, foam-like reticulum, not unlike that of a very 

 delicate bath sponge. 



The above account is based upon a single specimen in the National Collection, which shows 

 so many interesting features that it deserves a detailed description. It appears to be part of a 

 sector broken out of some larger flat ch'cular disc, which, however, may have had radial slits 

 running in from the growing edge. Although it is 20 cm. deep, there is no trace of the 

 method of attachment. It had been labelled M. expccnsa, Dana, by Briiggemann, apparently 

 because of the conical ccenenchymatous processes on the under surface, which Dana called 

 " appressed tubiform calicles." On the Museum specimen these processes are more like 

 ccenenchymatous papillae thaia. protuberant calicles, although it is true that here and there 

 calicles open at their tips. This single doubtful resemblance is- hardly enough' to identify 

 the two. Under the circumstances, in spite of the fact that nothing whatever is known of 

 the specimen, I prefer to- describe it in, detail in order to call attention to its structure. 



a.. Locality not recorded.. [Eegister No. 97. 9. 25. 3.] (Type.) 



For a description of the specimens in the Cambridge Museum, from Funafuti, which 

 appear to be related to the above, see the Appendix. 



