THE GENTJS ALVEOPOEA WITH THE EAYOSITID-aE. 511 



which the bud can start its own skeleton. In describing the 

 plan of this purely septate skeleton a number of fresh terms 

 have to be used. For instance, the edges of the septa outside 

 the thecal wall are called "costae," the word septa being confined 

 to the inner portions of these structures. The soft parts which 

 surround the costal skeleton, i. e. the sides of the body, are now 

 called the " edge-zone '*' or " Eandplatte " of v. Heider. These 

 terms are doubtless of some use, but it seems to me that their 

 significance is more topographical than morphological. With 

 regard to the budding, we find that the same lateral gemmation 

 which gave rise to what was called intracalicular gemmation, 

 when taken only in reference to the epithecate skeleton, may 

 become what is called extra-calicular in the thecate corals. I 

 do not, however, propose any changes in terminology, the exi- 

 gencies of description must settle such matters, and, with clear 

 conceptions as to the true morphological bearings of the subject 

 discussed, we can safely leave the cloud of words to be sifted 

 out by time. One rule seems to me very necessary in all future 

 discussions on budding, the terms should be used uniformly with 

 regard either to the poljp or to the skeleton. At present, when 

 the skeletons form the mass of the material to hand, it is better 

 to use terms relating solely to them. 



The Randjylatte. — As above stated, the rise from a basal epi- 

 theca of a septate skeleton within the polyp, naturally divides up 

 the space within the polyp into a central fossa inside the new 

 skeletal rampart and a peripheral region outside this rampart. 

 The region outside this internal skeletal rampart is what is 

 commonly called the edge-zone or Eandplatte. This view is 

 entirely in accord with v. Koch's contention* that the Eandplatte 

 has no important morphological significance, inasmuch as it 

 comes quite passi^^ely into existence owing to the complication of 

 the internal skeletal infoldings. The term, however, may be of 

 use topographically. I should be inclined to suggest that it 

 might with advantage be confined entirely to the lap which over- 

 flows the epithecal cup above described. 



The Epitheca. — The coimected account here given of the various 

 parts of the coral skeleton, viz. that the most complicated internal 

 skeleton bears the same relation to the primitive external epitheca 

 as do the complicated internal chitinous skeletons of certain 

 Arthropods (e. _^. the apodematous system of the Lobster, the 

 * Morpb. Jahrb. xiv. 1888 ; footnote on p. 342. 



