24 PROF. P. M. DUNCAN ON A NEW GENUS OE MADREPORARIA . 



4. On a new Genus o/Madreporaria (Glyphastr^a), with Remarks 

 on the Morphology o/Glyphastrjea Forbesi, Ed. Sf H.,from the 

 Tertiaries of Maryland, XJ. S. By Prof. P. Martin Duncan, 

 M.B., F.R.S., F.G.S., &c. (Read December 1, 1886.) 



[Plate III.] 



Many years since, the late Dr. S. P. Woodward drew my attention 

 to some very fine specimens of Septastrcea Forbesi, Ed. & PL, in the 

 British Museum, and lately a well-preserved specimen has beeD 

 sent to me from the Philosophical Institution at Scarborough. 

 There has always been a doubt in my mind regarding the classifi- 

 catory position of this large branching Tertiary species, and the 

 examination of the specimen lately sent confirms the impression 

 that the species differs so much from the Mesozoic Septastrcece that 

 it cannot remain in the same genus, although it must still be placed 

 in the Goniastra3oid alliance. 



The species mentioned in the 'Histoire Naturelle des Coral- 

 liaires ' by Milne-Edwards and Jules Haime, described by M. de 

 Eromentel in his ' Introduction a l'etude des Polypiers,' and pub- 

 lished by myself in the " Monograph of the British Eossil Corals " 

 (Pal. Soc. Lond.), with one exception, have the axial space nearly 

 or quite open, and the columella is either absent or very rudimentary. 

 But the species named after the late E. Forbes *, I find, has the 

 axial space completely closed, either by united septal ends with 

 some additional tissue, or by a columella, which, by uniting with a 

 number of septal ends and being increased in bulk by a remarkable 

 dissepimental tissue, forms a very projecting central mass in perfect 

 and full-grown calices. 



The genus Septastrcea originated with d'Orbigny in 1849, and 

 the diagnosis he gave was partly reproduced by Milne-Edwards 

 and Jules Haime in 1857 f. The species described in the first 

 instance were from the Eocene and Miocene of France and the 

 supposed Miocene of Maryland. A columella is not noticed in the 

 descriptions of any of these types, and it is said, in the generic 

 diagnosis, to be so definitely absent that the want clearly distin- 

 guishes Septastrcea from Goniastrma, Ed. & H. 



The following was the diagnosis published by Milne-Edwards 

 and Jules Haime from d'Orbigny : — " The corallum is either in the 

 shape of a convex mass or is subdendroid. The calices are poly- 

 gonal, and their margins are united to those of the neighbouring 

 calices and ordinarily show an extremely delicate line of separation. 

 The septa are large and appear to be formed of perfect lamina?, 

 and the endothecal dissepiments are well developed. Columella 

 and pali wanting. Multiplication by fissiparity." 



* M.-Ed. & J. H. Ann. des Sci. Nat. 3 e ser. t. xii. p. 164 (1850), and Hist. 

 Nat. des Oorall. vol. ii. p. 450. The fossils described were said to be in the collec- 

 tion of the Geological Survey of England and in the Bonn Museum, 



t Hist. Nat. des Corall. vol. ii. p. 449. 



