﻿MONTIPORA. 15 



as also large primaries, may be lamellate. The septa of the first cycle are often very exsert. 

 Fusion in the base of the cell of the spines or edges of the septa, especially of the directives, 

 occasionally takes place. In rare cases, the septal spines may fuse into or with a body which 

 has all the appearance of being a solid columella (see M. Mlisi). Martin Duncan's statement 

 that the calicles are typically provided with a columella is quite incorrect. Nor are there 

 any pali. 



The character of the margin is also a point worth attention : it may be sharply defined 

 or else a mere irregular break in the reticulum. The calicle may have a flat rim round it, ov 

 its inner wall may be continuous with the sides of the surface papillae, or ring of tnljercles 

 surrounding it. 



While true protuberance of the calicular wall very seldom occurs in Montiijora, all kinds 

 of papillfe occur, as hoods, underlips, and so on, on which or under which calicles may open. 



Variations in the cmnenchyma. — The chief surface specialisations in this have already 

 been described. There are four variations, quite distinct and yet shading off into one anotlier 

 in the following order : glabrous, foveolate, papillate, and tuberculate (for details see above, 

 p. 8). 



For purposes of classification, I have found it necessary to include some of the transitions 

 and to establish five divisions with sundry subdivisions. 



I. Glabrous, in which the surface is smooth. 



II. Glabro-foveolate, in which the foveolate appearance is not very marked, or perhaps 

 only confined to the younger portions of the stock where growth is very rapid. 



III. Foveolate, in which the interstices swell up into continuous or interrupted 

 ramparts. 



IV. Papillate. 



(a) In which the interstices swell up in irregular patches. 



(6) In which the papillae form hoods or underlips, &c., to the calicles. 



(c) In which the papillte run together to form ridges. 



{d) In wliich the papillae form regular rounded or nipple-shaped swellings. 



V. Tuberculate. 



(a) In which the tubercles are distinct. 



(h) In which the tubercles run together to form thin keels or ridges. 

 The systematic value of the various developments of these leading divisions is often very 

 puzzling ; as is also the value to be placed upon the variations in the fine texture of the 

 fcurface itself, which may be delicately or densely reticular, flaky, woolly, velvety, echinulate, 

 granular, and so on. For it is to be noted that the phenomenon mentioned in the preface to 

 the Catalogue of the genus Turhinaria (Vol. II. p. 18) is equally apparent in this case. 

 Certain types of surface texture and colour seem to characterise certain areas. The groups 

 of specimens from New Guinea, from Tonga, from the Macclesfield Bank, from Houtmans 

 Abrolhos, have in each case a curious resemblance to one another, due entirely to some 

 subtile surface character, which cannot be easily laid liold of. 



