﻿38 MADREPORAEIA. 



as pores of very different sizes, the largest about 1 mm., the smallest only faint specks. These 

 latter are young caUcles opening on the surface of the ccenenchyma ; the large calicles are 

 regularly circular or star-shaped. (See PI. XXXI. fig. 16.) 



The ccenenchyma is a light, wide-meshed reticulum, the threads of which tend here and 

 there to be flaky. 



c. Darros Island, Amirante Group, 22 fathoms, H.M.S. 'Alert.' 82. 10. 17. 124. 



broken coral. 



The coraUum in tliis specimen (c), which is a thick irregular block, seems to be due, as in 

 the last, to a tliin layer having enveloped a previous growth, without, however, always being 

 in close contact with it. WTiere the free edges are seen, at a few gaps in the under surface of 

 the mass, the layer is about 3 mm. thick and followed by an epitheca. Tlie whole stock seems 

 to have been free. On the upper side the coraUum is rapidly thickening by throwing up a 

 number of branchlets of all sizes and shapes. The lower portion of the mass appears as if 

 about to die down, when it would probably have again been grown over in its turn by coral 

 from the upper living portion. (PI. III. fig. 3.) 



The calicles resemble those of the last specimen (&), but are not so regularly circular or 

 star-shaped, and the septa are less regular. The calicles are very unevenly distributed, in 

 one place less than 1 mm., in another, 3 to 4 mm. apart. The ccenenchyma is closely but 

 delicately reticular ; on the lower portions, the ends of the threads expand into flat, jagged or 

 nodulated plates not unlike oak-leaves ; these together give the surface a solid appearance 

 and lead on to the formation of a film which creeps slowly up over the basal dying 

 portions. 



d. Marie Louise Island, Amirante Group, H.M.S. 'Alert.' 82. 10. 17. 215. 



17 fathoms, coral bottom. 



Specimen d isa nodulated mass broken away from its base to wluch it had been attached 

 by a narrow neck, and in many points resembling the specimen of M. solida. 



The calicles are rather more conspicuous than in the foregoing, the apertures being 

 apparently slightly sunk below the level of the ccenenchyma. They are of all sizes from 

 1 mm. to mere specks, and are about 2 mm. apart. The septa are very short solid projections 

 round a wide and deep fossa; they are arranged irregiilarly in two cycles almost equally 

 developed. 



The ccenenchyma is very solid, the threads of which it is composed being thick and 

 smooth ; the free ends stand up as stout echinulte. The specimen is somewhat heavier than 

 the foregoing, which are as light as or even lighter than pumice stone. 



e. Darros Island, Amirantes. ' H.M.S. 'Alert.' 82. 10. 17. 190. 



/. Marie Louise Island, Amirante Group, H.M.S. 'Alert.' 82. 10. 17. 205. 



17 fathoms, coral bottom (in four pieces). 



Two branched specimens (e, f), the branches being cylindrical, with a slight tendency to 

 flatten out fan-shaped at the tips. In specimen /, which was a large specimen, unfortunately 

 broken, the basal piece is retained ; it is found to be closely encrusting a prominence (branch ?) 



