Mr. H. J. Carter 07i the Stromatoporidse. 307 



calicles respectively, and, besides being in direct communica- 

 tion with the vermicular spaces of the curvilinear coenenchyma, 

 which open into them all round, are more or less divided 

 transversely into compartments bj calcareous septa (often 

 surmounted bj a stylous process), which have been called 

 "tabulae," each compartment indicating the successive deve- 

 lopment of a poljpite or hydranth ; hence the term " tabu- 

 lated " has been applied to them. (This is a common feature 

 of the tubes of Heliolites^ Halysites, and Favosites.) Lastly, 

 the "superficial structure," which is the surface-layer, is 

 formed exactly like the " middle structure," only that, being 

 actually under growth, it is less compact, whereby the trans- 

 verse sections of the larger branches of the " proliferous mem- 

 brane," or hydrophyton, are rendered more visible between it 

 and the outer margin of the " middle structure " than in the 

 layers of the latter. 



Turning now to an examination of the branch longitudi- 

 nally, we may reverse the order of the descri{)tion ; and taking 

 the " superficial structure " first, we observe the same curvi- 

 linear character of the elementary composition of the ccenen- 

 chyma as before mentioned, but more open and, where de- 

 finitively formed, presenting, sometimes on the surface and 

 generally in the deeper parts, a convoluted appearance of the 

 typical curvilinear character, in miniature like the convolu- 

 tions of the brain, united by transverse processes or bars — in 

 short, very much like the remains of a thoroughly worm-eaten 

 piece of Avood, — but where imperfectly formed, as on the 

 surface chiefly, more or less spined, owing to its being formed 

 in the first place of small, nodose, bacillar, and branched (?) 

 calcareous spicules, which, before they become entirely incor- 

 porated into fibre, project more or less beyond the surface of 

 the latter (accounting, perhaps, for the granular and cribriform 

 appearance of the fibre in Caunopora &c., that will hereafter 

 be mentioned), subsequently passing into the typical curvi- 

 linear form, and finally, more internally (that is, in the 

 " middle structure"), into a solid crystalline state with radiated 

 structure, like that represented by Mr. Moseley {op. et loc. cit. 

 pi. 2. fig. 8), in which no trace of the original spicular element 

 remains, as in Tuhipora musica — a transition first mentioned 

 by Ellis in the red coral {Corallium rubrum), who states that 

 he received the "hint" from Dr. Donati (Ellis and Solander, 

 'Nat. Hist, of Zoophytes,' 1786, p. 78). 



This can be well seen in Millepora alcicornis with an inch- 

 focus compound power, magnifying about 100 diameters, 

 probably better in the living than in the dried specimen, 

 where, unless protected by the overgrowth of a piece of 



21* 



