3 24 TABULATE CORALS. 



in all the corallites, the tabulae being complete and remote, 

 and sometimes placed at corresponding levels in many of the 

 tubes. 



From M. undulata the present species is distinguished by 

 its concavo-convex or regularly hemispherical form, by the 

 more rapid intercalation of the new tubes, and by the greater 

 abundance of the tabulae, while it never attains the dimensions 

 or assumes the lobate habit of the former. 



I have named the species in honour of Herr Winter of 

 Gerolstein, from whom I received much friendly assistance 

 while collecting in the Eifel. 



Formation and Locality. Not uncommon in the Devonian 

 of Gees, near Gerolstein, Eifel. 



Genus PRASOPORA, Nich. and R. Eth., jun., 1877. 

 (Ann. Nat. Hist, ser. 4, vol. xx. p. 38.) 



Gen. Char. Corallum compound, concavo-convex or hemi- 

 spheric in form, composed of numerous prismatic corallites 

 radiating from a wrinkled basal epitheca. Corallites of two 

 kinds, large and small, 1 regularly and uniformly intermingled 

 throughout the entire colony. No " monticules " or clusters of 

 large tubes. All the corallites thin-walled, and prismatic or 

 angular in shape ; the large tubes furnished with an exterior 

 zone of vesicular tabulae surrounding a vacant central tube, 

 which may be crossed by an occasional tabula. Small corallites 

 arranged in a zone (rarely or never quite complete) round the 

 large tubes, and crossed by numerous close-set, complete, and 

 horizontal tabulae. 



1 In our original description of Prasopora (loc. tit.}, as well as in our " Mono- 

 graph of the Silurian Fossils of Girvan," Fasc. I., p. 44, Mr Etheridge and I em- 

 ployed the term of " coenenchymal tubuli " for the small corallites. We did so, 

 however, simply in conformity with the nomenclature employed by Milne-Edwards 

 and Haime, and we expressed the opinion that the small tubes are " really of the 

 nature of rudimentary corallites, which contained in the living state a series of 

 small and specially modified zooids." 



