CALCAREOUS SKRLETON OF THE ANTHOZOA. 501 



no doubt that the structures in question are identical with von 

 Heider's second kind of calicoblasts. 



In 1888, in a paper on the anatomy of Mussa and Eu- 

 phyllia (2), I described the presence of elongate columnar 

 calicoblasts on the upper and peripheral parts of the septa of 

 Mussa distans, and at the same time I criticised von 

 Heider^s interpretation of the striated wedge-shaped bodies as 

 calicoblasts, pointing out that I had found precisely similar 

 structures in Mussa, but never in the region of most active 

 coral growth. On the contrary, they were always associated 

 with the mesogloea of the mesenteries ; and, moreover, the strise 

 could not be due to the presence of spicules of carbonate of 

 lime, for they were unaltered after prolonged decalcification. 

 At the same time Fowler (8) referred to the existence of 

 similar wedge-shaped structures in Pocillopora brevi- 

 cornis, and gave his opinion that they were rather connected 

 with the attachment of the mesentery to the corallum, than 

 with the secretion of carbonate of lime. In the same paper 

 Fowler described and gave a diagrammatic figure of elongated 

 columnar calicoblasts in Lophohelia prolifera. In a sub- 

 sequent paper (9) Fowler described and gave careful drawings 

 of the striated structures in Stephanophyllia formo- 

 sissima and Flabellum alabastrum, and pronounced them 

 to be nothing more than offshoots of the homogeneous meso- 

 gloea of the mesentery, possessing neither nucleus nor cell- 

 wall. He held that their occurrence only in the neighbour- 

 hood of the lines of attachment of the mesenteries, their 

 position, shape, and striation, indicated that their function was 

 to provide an increased surface for fixation of the mesentery, 

 and a firmer fulcrum for the action of the powerful retractor 

 muscles. No further observations of importance were made on 

 the subject till 1896, when Mrs. Gordon (formerly Miss Maria 

 M. Ogilvie) published a long and minute account of the micro- 

 scopic structure of various types of Madreporaria (25), and 

 suggested an entirely new classification of the group founded 

 upon the microscopic characters. Mrs. Gordon rejects 

 Fowler's and my accounts of the striated structures, and says 



