564 R. F. TOMES OUT MADREPORARIA PROM THE CORAL RAG 



pass and from which they are very clearly distinguishable. This tissue 

 assumes a concentric arrangement, something like a series of rudi- 

 mentary walls, one within the other, as in Litliostrction, in which 

 genus it was placed by its first describer. Sometimes the inner ring 

 of endotheca is more fully developed than the others, simulating an 

 inner wall ; but this is not constantly the case, or it would furnish 

 grounds for the creation of a new genus. 



There are two species of Corals figured by Eeuss from the Cre- 

 taceous bed of Gosau, under the names of Prionastrcea Hornesi an 

 Isastrcea profunda*, in which the same kind of dissepimental 

 structure appears as in the present species. Both of these have 

 been subsequently referred to the genus Isastrcea by MM. Milne- 

 Edwards and Hairnet; and the similarity of structure between 

 these Cretaceous species and the Portland one is so considerable, 

 that the latter is most likely quite as nearly affined to the Cretaceous 

 as to the Oolitic forms of Isastrcea. 



In the series of papers which I have prepared on the Madreporaria 

 of the Jurassic formations of this country, and which have been 

 read before this Society, the following new genera have been pro- 

 posed : — Tricycloseris, PhyUogyra, Phylloseris, Bathyccenia, and 

 Crateroseris. Eleven other genera, not themselves new, but before 

 unknown in the Jurassic deposits of England, have been made 

 known. They are Epismilia, Donacosmilia, Cyathophyllia, Con- 

 fusastrcea, Chorisastrcea, Thecoseris, Oroseris, Dimorpharcea, Lati- 

 mceandrarcea, Enallolwlia, and Favia. Goniocora, before unknown, 

 excepting in the Coral Rag, has been found in the Inferior Oolite ; 

 and Astrocoznia has been added to the list of Great-Oolite and Coral- 

 Bag genera. 



With the present communication ends a series of papers, which 

 have been a long time in hand, and are the results of a protracted 

 and often repeated examination of a very extensive collection of 

 specimens, mostly of my own collecting, and about the locality and 

 stratigraphical position of which there cannot therefore be any 

 uncertainty ; but I am sorry to be obliged to add, in conclusion, 

 that I have not myself as yet had the opportunity of collecting in 

 many of the localities from which the Coral-Rag species have been 

 obtained. 



DESCEIPTION OF PLATE XXII. 



Fig. 1. Thamnastrcsa concinna: a portion of a worn corallum of the natural 



size, seen from above. 

 2. : a vertical section of a tall portion of a corallum, natural 



size, showing the arrangement of the corallites. 



3. : some calices, magnified. 



4. : some calices much worn, showing the prominent columella, 



magnified. 



* Beitr. Kreidesch. Ostalpen. p. 116. 



t Hist. Nat. Corall. t. ii. pp. 530 and 534. 



