Prototheca of the Madreporaria. 25 



essentially the same as that shown in fig. 14, but the proto- 

 theca was shallow and open and the soft parts had bagged 

 over the low walls on to the ground^ doubling them as shown 

 in the figure. Large wing-like septa come over the wall and 

 also reach to the ground or to the rim of the epitheca all 

 round outside. Between these flange-like septa, as they grow 

 upward and outward, the polyps leave one basal secretion 

 after another, so that both inside the cup and outside it there 

 is an increasing thickness of vesicular tissue. In the diagram 

 (fig. 15) the lines are drawn as so many distinct tabulse. 

 But it would hardly be expected that the successive detach- 

 ments of the polyp would take place simultaneously within 

 each interseptal loculus, right from the centre of the calicle 

 over the edge of the theca down to the ground. But as 

 dissepiments are only portions of tabulae, the diagram is the 

 best way of illustrating the facts. This type of structure, in 

 which the vesicular tissue not only rises between the septa 

 within the calicle, but also thickens the column between the 

 costffi outside it, is that which lies at the base of Lithophyllia. 

 It is true that emphasis has not hitherto been laid upon this 

 point, for the sim)>le reason that the ])rotothcca had first to 

 be discovered. Milne-Edwards and Haime merely remark 

 that dissepimental tissue is very abundant, wiiile their classing 

 Mussa with Lithophyllia shows clearly indeed that the 

 arrangement of the dissepimental tissue had not been analyzed. 

 On tiie other hand Knorr, to whose figure among others 

 Milne-Edwards and Haime refer as a type of L. licera, 

 mentioned the "stony films round the foot " and described 

 the impression made upon him by the words " new crowns 

 continually covered up the old ones^ The meaning of this 

 otherwise enigmatical saying is quite clear when we glance 

 at the diagram (fig. 15) here given. We conclude, then, 

 that there is no generic difference between Moseleya and 

 Lithophyllia and that tlie genus Moseleya is superfluous. At 

 tlie same time it is due to Mr. Quelch to point out, (1) that 

 the analysis of the essential structure of Moseleya was hardly 

 to be discovered from the single specimen at his disposal at 

 the time, and (2) if it had been, there was no existing descrip- 

 tion of Lithophyllia which would greatly have helped him. 

 'i'he calicle of which he made a section was old, very much 

 flattened, and souiewluit distorted, and with the tissue on its 

 exposed side largely killed down. This latter point is of 

 gieat importance, for it is the structure of the sides of the 

 column winch is essential to a correct diagnosis. Once, 

 however, the clue is given, which is supplied in abundance 

 by the new specimens, the structure is easy to comprehend. 



