420 G. HERBERT FOWLER. 



On some Structures previously described as Calicoblastic. 



The only other point of interest noticed in Stephanophyllia 

 is a structure for the firmer attachment of the mesentery to 

 the corallum, a structure which occurs in many other genera, 

 though a different significance has been hitherto assigned to it. 

 InFlabellum alabastrum it is especially well developed, and 

 consists of a series of processes given off radially into the 

 corallum by the mesoglcea lamina of the mesentery (fig. 7). 

 These processes are generally laminated, presumably for a 

 further increase of the surface of attachment, and are directed 

 obliquely downwards. In transverse sections of decalcified 

 specimens of Flabellum and similar forms they often appear 

 as a layer of polygonal bodies, striated as a rule radially, and 

 lying between the mesoglcea and the space occupied before 

 decalcification by the corallum (fig. 8). Such bodies were re- 

 cently described by W. L. Sclater (' Proc. Zoo). Soc./ 1886) in an 

 account of Stephanotrochus Moseleyanus as calicoblasts 

 or coral-forming cells ; but vertical sections, cut parallel to the 

 broader plane of the mesentery, show that such an explanation 

 is untenable. A calicoblast is ontogenetically derived from 

 the basal ectoderm of the embryo, and presumably has the 

 characters which we ordinarily associate with a cell. A layer 

 of such calicoblasts, obviously true cells, may be recognised at 

 the growing points of any coral. The structures in question, 

 however, are merely offsets of the homogeneous mesoglcea of 

 the mesentery, and possess neither nucleus nor cell wall ; nor 

 is the mesoglcea of the Anthozoa, itself a secretion, known to 

 exhibit secretory activity. Again, these processes do not occur 

 at the growing points of the corallum. On the other hand, as 

 they are to be met with only in the neighbourhood of the lines 

 of attachment of the mesenteries to the corallum, their posi- 

 tion, as well as their shape and lamination, indicate that their 

 function is to provide an increased surface for fixation of the 

 mesentery, and a firmer fulcrum for the action of the powerful 



