TURBINAKLE FOLIATE. 49 



Calicles may be very prominent on cylindrical or protuberant portions of the stock, but 

 on the faces of the fronds liardly projecting or with only the margin projecting, or again, only 

 the dorsal margin standing out so as to allow the calicles to look somewhat upwards. 

 Aperture oval, great variation in length of long diameter (from ca. 3 mm. max.). Septa (20) 

 thick and regular, not reaching to the half-radius circle, descending more or less abruptly and 

 vertically round a generally deep oval fossa with a well-marked columella. The interseptal 

 loculi short-oblong, with well-defined peripheral margins. 



Cccnenchyma thick, granular or echiuulate ; ridges well developed and of regular thickness, 

 separated by deep furrows. 



The diversity in the appearance of these corals is so great, that, but for the fact that they 

 are connected together by intermediate forms, tliey would certainly be made to yield tliree or 

 four species. An encrusting mass throwing up four or five tail cylinders would not be classed 

 either with another sending up a confused mass of finger-like processes, or with a mass of 

 erect and sinuous fronds. Yet all these diversities occur, but fortunately linked together by 

 forms showing more than one method of growth in one and the same stock. 



The variations in the sizes of the calicles are also very great. One cylinder will be 

 covered with minute calicles, another near at hand, on the same stock, with large calicles. 



One remarkable feature is the great similarity between this species and T. conspicua in 

 the character of the calicles and of the ccenenchyma ; so like, indeed, are they, that it is 

 probable some of the many young forms which I have labelled T. conspicua may well be the 

 early cups of T. magna, it being impossible to say into which form they might develope. 



T. magna, however, seldom if ever develops the bifrons type of fold, and T. conspicua 

 does so almost without variation. Had there been any variation in T. conspicua showing the 

 formation of fronds without the bifrons folding, the two species would have shaded off into 

 one another. 



A remarkable variation is found in the arrangement of the fronds in the more foliate 

 specimens. The fronds in some are so arranged that the polyp-bearing faces are all exposed 

 to the view, the under faces (free from polyps) being apposed and inconspicuous. In others, 

 the reverse is tlie case : the bare under surfaces form great open hoUows and valleys, while 

 the polyp-bearing faces are so close (even fusing) as to be quite inconspicuous. These two 

 strikingly different methods of growth are connected by intermediate stages, so that they 

 have to be looked upon as accidental and of no specific value. 



The old parts of the fronds and cylinders die away, and a wide living zone persists, 

 forming along its lower edge a slight shelf, as if trying to curl up. 



Most of the specimens are much infested by a species of Balanus. 



The name was suggested by the large size of some of the more conspicuous fronds, which 

 give these particular stocks a very imposing appearance. 



A. Masses of irregular fronds \vith occasional formation of protuberances and cylinders ; upper 

 faces of fronds most conspicuous. 



a. Shark's Bay (with T. conspicua). SaviUe-Kent Coll. [94. 3. 9. 4.] (Type.) 



h-e. Shark's Bay (with T. conspicua). Saville-Kent CoU. 



/. (A fragment) Wednesday Island, Torres 



Straits, 8 fathoms. II. JI.S. ' Challenger.' 



H 



