﻿GLABROUS MONTIPORiE. 25 



them is briefly described by Bassett Smith, who suggests its affinity with M. lichen* But 

 Dana's type had " subtubiform calicles " and was much thicker. 



These are remarkable on account of the enormous depth at which they are found, and 

 also because they are the thinnest and most delicate of all the known Montiporans. 



a. Macclesfield Bank, China Seas, 35 to 41 fathoms. 'Coll. Bassett-Smith. (Types.) 



&. Macclesfield Bank, China Seas. „ „ 



c. Macclesfield Bank, China Seas, 40 fathoms. . „ ,, 



7. Montipora porosa. (PI. I. fig. 4; PI. XXXI. fig. 7.) 

 Montipora porosa, Bassett-Smith, Ann. and Mag. Nat. Hist., vi. (1890) p. 451. 



Description. — Corallum, complete form unknown, explanate, thin, translucent, with points 

 of light passing through near the edge, expanding freely, of nearly even thickness, 2 mm., 

 irregularly wrinkled, fine wrinkles running radially and a tendency to coarse wrinkling 

 concentrically ; unsupported by an epitheea. 



Calicles hardly visible to the naked eye ; with a lens, they show as minute (less than 

 0*4 mm.) inconspicuous star-like arrangements of the surface ©f the ccenenchyma, very 

 irregularly scattered, at times far apart, here and there not more than 2 mm. from one 

 another. In younger and thinner fronds, the calicles can be seen as minute dark points ; 

 these disappear with the thickening of the coenenchyma. The septa are very irregular, 

 projecting inwards from the ring of surface granules; sometimes the six primaries are 

 distinct, at others there are more than six, but no clear distinctions can be made out between 

 primaries and secondaries. The fossa appears quite shallow. 



Coenenchyma shows, in section, the outwardly streaming reticulum, which is loose, light, 

 and open meshed, but much denser towards the under surface. There being no epitheea, the 

 under surface is slightly porous and a few minute calicles open in it. The upper thickening 

 layer is only slightly developed, the horizontal streaming layer fornaing the bulk of the thin 

 corallum. The upper surface looks smooth and velvety to the naked eye, but is composed of 

 evenly distributed granules, between which the pores are but faintly visible. There is a 

 distinct tendency of the granules to run in series towards the growing edge. On the under 

 surface, the granules are more minute and the pores are larger and more conspicuous. 



There are three specimens which can perhaps be classed under this heading. The largest 

 (a) is a fragment broken off from the growing edge of some stock, the complete form of which 

 is unknown. Though some 7 cm. across and 10 deep, there is no trace of any supporting 

 epitheea. Strength for so large an expanse of coral seems to be gained by concentric wrinkling, 

 the edge hanging down and then turning up again. In the lower angles of the wrinkles the 

 ccenenchyma tends to send down pendent drops. 



* Ann. and Mag. Nat. Hist., vi. (1890) p. 450. 



