30 EKOF. P. M. DUNCAN ON A NEW GENUS OE MADREPORAEIA. 



and, rarely, some members of a fourth. In the first instance the 

 primaries and secondaries reach the. axis, and the tertiaries do not 

 project much from the wall. Commonly, in full-grown calices, 

 two long slender opposite primaries unite with the columella so as to 

 cross the calice, having the appearance of one very long septum ; 

 in other calices the columella unites several septal ends, and the 

 appearance just noticed does not occur ; or opposite primaries may 

 unite without a columella. The inner parts of the septa are slender, 

 often wavy, and their granular free part is very low, on account of 

 the occurrence of dissepiments ; upper dissepiments free and gra- 

 nular, uniting with the septa and columella to form a convex mass at 

 the bottom of the calice. 



Fissiparity rare, and when gemmation occurs the buds have six 

 primaries ; height many inches ; breadth of the stem 28 to 32 or 

 more millim. ; breadth of calices from 1*5 to 6 millim. ; depth 1*5 

 to 3 millim. 



Locality. Maryland Tertiary deposits. 



The only notice which I can find in any American publication of 

 Septastrcea Forbesi, Ed. & H., now Glyphastrcea Forbesi, Ed. & H., 

 sp., is in the " Check -list of the Invertebrate Eossils of North 

 America," by Meek, Smithsonian Miscellaneous Coll. vol. viii. 1884, 

 "Tert. Syst. Miocene Epoch." But there is nothing more than the 

 name and the locality of Maryland mentioned. The form does not 

 appear to have been figured anywhere. 



Lyell was the first geologist who introduced the corals of Virginia 

 and Maryland to the notice of science, and Lonsdale studied the 

 forms. Lyell's communication is in the fourth volume of the Pro- 

 ceedings of this Society, p. 547 (1845), and Quart. Journ. Geol. Soc. 

 vol. i. 1845, p. 413. Amongst other corals Lyell collected from 

 Virginia a compound, ramose, cylindrical, lobed or massive and 

 expanded species, which Lonsdale, in a paper in the same volume 

 (p. 497), described as Columnar ia (?) se.vradiata. He figured the 

 form and gave a magnified view of a calice. 



I do not think that Edwards and Haime had the opportunity of 

 studying Lonsdale's type, otherwise they would not have placed it in 

 such a remote genus as Astrangia. It appears, after studying 

 Lonsdale's careful description, that Meek is correct in placing the so- 

 called Columnaria in the genus Sejjtastrcea, as understood by Milne- 

 Edwards and his school, although Lonsdale stated that he could not 

 find proofs of fissiparity on the surface of the corallum. The mag- 

 nified view of the calice given by Lonsdale shows a small columella 

 and the stout parts of the primary and secondary septa near the 

 margin ; moreover he figures and mentions a groove which bounds 

 the calices ; but there is union shown between some of the tertiary 

 septa and the secondaries which does not occur in the calices of the 

 other species. Moreover the open condition of the interseptal 

 spaces of the immature calices of Lonsdale's species is not seen in 

 G. Forbesi; nevertheless the alliance of the species is very close. 

 It appears to me that Lonsdale's species must stand as GlyphastrcBa 

 sexracliata, Lonsd., sp. The type of Lonsdale's species is not in the 



