364 PEOP. p. M. DTJlSrCAlS" OISI THE EPITHECA 



form just described. Provisionally tlie variety pachycliila roust 

 be separated from the Cop-lorics ; but until further researches are 

 completed, I do not propose to establisb a new genus. 



Leptoeia phetgia, MUs Sf Colander, Hist, of Zoopli. pi. 48 ; 

 Milne-Edwards Sf Jttles Haime, Hist. Nat. des Gorall. vol. ii. 

 p. 406. 



The specific characters of this form were given by Milne- 

 pjdwards and Jules Haime ; and the specimen under considera- 

 tion comes within their diagnosis. In the definition of the genus 

 those authors remark: — " Le plateau inferieur est revetu d'une 

 epitheque mince mais complete." They of course notice that the 

 series of corallites unite with their neighbours by their walls. 

 According to these descriptions, it is implied that whilst each 

 individual is soldered by its flanks to its neighbours, the whole 

 colony or corallum rests on a common plateau clothed with an 

 epitheca. Presumably there is a theca or basal wall from which 

 the calicular or, rather, serial walls arise. 



An examination reveals a different state of things ; for on 

 removing the epitheca, which is thin, opaque, and marked with 

 undulating grooves and linear elevations, no trace of a theca, wall, 

 or plateau can be found. 



The epitbeca covers a considerable surface, and above it, in 

 the lowest position of the corallum, are the lower ends of 

 septa, the interserial walls, and the lamellar columellse, and all 

 these are united by dissepiments which give a cellular appearance 

 to the whole. In fact, the epitheca is the onlv basal structure ; 

 there is no plateau like a theca ; and the upward growth occurred 

 from the thin opaque structure which covered every thing on the 

 stone upon whicb the coral grew. The epitheca was not adhe- 

 rent in many places to the foreign body. The ridges between 

 the long and rarely sinuous serial corallites are narrow, and 

 septa cross them from one series to those on either side. In tiie 

 long axis of each ridge is a slender wall which reaches upwards 

 to within a millimetre of the free denticulate septal edge. The 

 septa project at right angles to the wall on either side of it: 

 and on their vertical edge are stout nodular projections, which 

 are recognized on the upper part of the septum where it joins 

 its fellow over the wall as simple dentations. The nodular pro- 

 jections may be seen to unite with corresponding structures on 

 the sides of the slender lamellar columella. This has a thin and 



