CORALS FROM THE CORAL RAG. 



2. Stylina Delabechii. Tab. XV, figs. ], la, Id, Ic. Id. 



Corallum massive, convex, seldom subgibhose, and sometimes composed of a series of 

 thick superposed layers ; common basal plate or wall covered with an epitheca presenting 

 concentric folds, and appearing to have been complete originally. Calices not projecting 

 much, nor closely set, and placed at very unequal distances from each other. Cosfa sub- 

 granulose, shghtly prominent, rather closely set, straight, or slightly curved towards their 

 lower end, and alternately larger and smaller; the former corresponding to the septa of the 

 last cyclum : those of adjoining corallites meet at the bottom of the intercalicular spaces, 

 but remain in general distinct. Calices quite circular, but rather unequal in size, especially 

 in different specimens ; fossula large, open, and rather shallow. Columella styliform, slightly 

 prominent, somewhat compressed, and quite distinct from the septa. Three complete septal 

 cycla, and the elements of a fourth cyclum in two of the six systems. The secondary septa 

 very little developed in the four small systems, but becoming as large as the primary ones in 

 the two other systems, so as to form with these eight principal sejjta, which are somewhat 

 exsert, thicker at their inner and outer edge than in the middle, and quite straight. The 

 secondary septa are small and delicate ; those of the last cyclum are rudimentary, but are 

 represented externally by well-developed mural costse, which are even larger than those 

 corresponding to the sejjta of superior orders. A vertical section of the corallum shows 

 that the intermural spaces are principally filled up with exothecal tissue and costal laminae, 

 but present also some horizontal prolongations of the walls forming ill-defined strata. The 

 septa are composed of non-perforated laminae, and the dissepiments, which are horizontal, 

 correspond to each other in the different interseptal loculi, so as to divide the visceral 

 chamber into a regular series of superposed spaces, somewhat as in the CyathopliijllidcB. 



The diameter of the calices varies from 1 to 2 lines, and the breadth of the inter- 

 calicular spaces is often double that size. 



The specimens which we have examined were found at Steeple-Ashton, and belonged to 

 the collections of the Museum of Practical Geology, the Geological Society of London, the 

 Bristol ]Museum, Mr. Phillips, Mr. Bo\\'erbank, Mr. Stokes, Mr. Walton, Mr. Sharpe, 

 Mr. Pratt, M. de Koninck, and the Paris JVluseum. 



Stylina Delabechii xs, easily distinguished from most of the other species belonging to the 

 same genus, by the existence of eight apparent systems. The same character is met with 

 only in S. ramosa' and in S. Liigdiinensis.^ The first of these species is of a subdendroid 

 form, its calices are unequal, rather distant, and a little more than a line in diameter; the 

 total number of the septa is only sixteen. As to S. Luydimensis, the specimen from whicli 

 the characters were taken is in a very bad state of preservation, and we are not able to add 



* Pseudoccenia ramosa, and /'. duj'itata, D'Orbigny, Prod., vol. ii, p. 34. 

 - Octoccenia Lv(/dtinensis, D'Orbigny, Prod., vol. i, p. 222. 



