1886.] MADREPORARIAN CORAL. 135 



that all the hard parts of the coral are laid down by these cells, 

 which can be always found between the mesodermal lamella and 

 the hard parts. Koch (9) showed that the calycoblasts were really 

 the remains of the basal ectoderm-cells of the embryo, so that the 

 whole of the corallum is laid down by ectoderm, and is really, mor- 

 phologically, outside the coral. This of course corrects the old view 

 which regarded the basal ectoderm of a coral as having disappeared 

 from the outside of the corallum, since what remains of the basal 

 ectoderm is really within the corallum, and is the very means of 

 forming the corallum. Koch (9, plate xx. fig. 9) gives a repre- 

 sentation of three calycoblastic cells, which seem to be merely ordinary 

 high epithehal cells, nucleated and filled with granules. 



I have found everywhere between the corallum and the mesoderm 

 lamella a tissue or series of cells, represented in Plate XIV. figs. 10-13, 

 cal. ; these I btlieve to be the calycoblasts described by Heider and 

 Koch. That these cells must be calycoblasts is, I think, evident 

 from their position, since they are everywhere found between the 

 corallum and the mesoderm lamella. But in form they are very 

 different from the calycoblasts figured by Koch, for, whereas Koch's 

 calycoblasts are, as was said above, ordinary granulated epidermic 

 cells, the cells which I have found in Stephanotrochus are not 

 quadrangular but of irregular shape, and separated from one another 

 by intervals, so that they seldom form a definite layer ; also they are 

 striated in a most extraordinary way, as is shown in figure 12. 



Whether these cells are the calycoblasts of Koch I cannot with 

 certainty say ; it may be that the difference of appearance is due to 

 the fact that Koch's figure represents these cells in a very young state, 

 when they are doubtless more active than in the adult coral ; or, 

 again, the calycoblasts of Koch's form Asteroides may differ essen- 

 tially from those of Stephanotrochus. The fact is, however, that 

 until more is known of the anatomy of other corals, it is impossible 

 to decide on the nature of these cells. 



In conclusion I must thank Prof. Moseley for kindly allowing me 

 to examine this coral, also for his advice and assistance ; so, too, I 

 must record my obligations to Prof. Ray Lankester, and my friend 

 Mr. Fowler, for mucli help. 



I append a list of the principal publications referred to ; I have 

 abstained from quoting the views and discoveries of the last few 

 years with regard to Madreporariau corals, since a very complete 

 history of recent researches on the subject will be found in Mr. 

 Fowler's paper (4). 



VI. List of Publications on the subject. 



1. Moseley, H.N. Report on certain Hydroid, Alcyonarian, and 



Madreporarian Corals, procured during the voyage of H.M.S. 

 'Challenger.' — Report of the Voyage of H.M.S. 'Challenger,' 

 Zoology, vol. ii. 1881. (De&cv'i'piiono^ Stephanotrochus, p. 151.) 



2. TiZARD and Murray. Exploration of the Faroe Channel during 



the summer of 1880 in H.M's hired ship 'Knight Errant.' — 

 Proc. Royal Soc. Edinburgh, no. 111. p. C38. 



3. Martin Duncan, P. A Revision of the Families and Genera of 



