556 James Thomson — JVew Carl>oniferous Corals. 



IV. — Desokiptions of New Corals from the Caeboniferous 



Limestone of Scotland. 



By Jas. Thomson, F.G.S. 

 Corr. Memb. E. See. Sci. Liege, Belgium. 



(PLATE XX.) 



'AVINGr been engaged for many years in collecting and studying 

 the corals of the Mountain Limestone of Scotland, I propose, 

 in the present communication, to describe some of the new species 

 which have come under my notice. Some of these were discovered 

 in a thin bed of shale from five to nine inches thick, which overlies 

 the low post of limestone in Trearn Quarry, near Beith, Ayrshire. In- 

 deed, this horizon throughout Great Britain may be safely said to be the 

 zone in which simple corals existed in greater abundance, and at- 

 tained greater dimensions, than in any other section of the Mountain 

 Limestone. There are a few forms found in the upper members of 

 the period. So far, however, as my investigations have gone, these 

 are limited both in genera and species ; and, with only one or two 

 exceptions, are all more or less simple in their organization. It is 

 not my intention at present to enter into any elaborate strati- 

 graphical arrangement of beds, or classification, or distribution 

 of the difi"erent genera or species. That will form matter for 

 a memoir, in which I hope to delineate not only the almost im- 

 perceptible gradation from one species into another, but also the 

 persistent modifications that occur between the difi"erent genera. 

 Indeed, those modifications are so constant, that it often becomes 

 difficult to say where one genus begins, and its next ally ends. This 

 is a result that can only be safely attained by examining an exten- 

 sive collection of specimens, all of which must be sectioned with 

 great care. From my own personal observations, assisted by my 

 friends, I shall be able to note the stratigraphical distribution of the 

 genera and species throughout the three kingdoms. Such a memoir 

 is a great desideratum ; and it can only be prepared from personal 

 investigation and examination of sections. Only thus can we ascer- 

 tain in what condition the genera and species are found. 



In the mean time, I intend giving brief descriptions of some new 

 genera and species which I have discovered. Some of these have 

 been noticed in my Eeports on the investigations into the Mountain 

 Limestone Corals, in the Eeports of the British Association. And 

 here I beg to acknowledge the kindness of the Council of the Asso- 

 ciation, shown in their making money grants to assist me in my 

 investigations. 



Family : CTATHOPHYLLID^. 

 Tribe : Eodophyllesia. 

 Genus : Podophyllum. 

 Generic cliaracters. — Corallum cylindro-conical, usually tall, fre- 

 quently from eight to ten inches long; curved, and presenting 

 well-marked accretion ridges, Epitheca thin and smooth. Calice cir- 

 cular, shallow, and slightly everted. Septa thin, numerous, and formed 



