GQ Dr. Wheeltoii Hind — Carhoniferous Life- Zones. 



D is a bed of crinoidal limestone. 



E is a bed of dolomitic crinoidal limestone. 



F is a tbick oolitic limestone, wbich is considered to correspond 

 ■with the base of the Visean, with Productus cora in the lower part 

 and P. giganteus above. 



In this succession. Dupont's Waulsortian division of Belgian rocks 

 is entirely absent, and the chief features on which the identification 

 of the two series of beds is based are purely petrological, and not 

 palaeontological. There are so many horizons at which beds of 

 crinoids occur, that unless species can be recognized, such statements 

 are utterly valueless for the purposes of identifying horizons. 



The Avon section shows the following sequence : — 



Zone oj Productus cora | jj^^^^^^j^ Limestone, 2,000 feet, 

 and P. giganteus ) 



Productus giganteus and | ^^^^^ Limestone Shales, 500 feet. 

 P. cora absent ) 



In a paper published in the Annales du Soc. geol. de Beige, torn, ix, 

 1881-2, p. 31, De Koninck, describing some new Cephalopoda from 

 the Carboniferous Limestone of Ireland, gives three lists of fossils 

 which he considers as typical of the three series of beds established 

 in Belgium by Dupont, and states that he is able to make out the 

 same three zones in Ireland from the study of specimens in various 

 museums and collections. He considers that the following parallels 

 occur : — 



Ireland. Belgium. 



1. Limestone of Armagh. Calcaire des Ecaussenes et 



de Comblain au Pont. 



2. Calcareous schist of Hook Point. Calcaire de Tournai. 



3. Limestones of Eathkeale and Calcaire de Waulsort. 



Co. Limerick. 



4. Limestones of Cork, Dublin, Calcaire de Yise. 



Galway, and Meath. 



If a comparison be made between the lists of Carboniferous fossils 

 from these districts which were drawn up by the late Mr. Baily for 

 the Memoirs of the Irish Geological Survey, it will be seen at once 

 that no such palasontological divisions can be shown for the Irish 

 Carboniferous beds. Indeed, most of the species on which 

 De Koninck relies for the identification of his three life-zones are 

 not confined to the horizons which he mentions. For example, 

 Zaphrentis cylindrica, Syringothtjris distans, Spirifer laminosus, Athyris 

 Boyssii, A. lamellosa, and Orthis Mtchelini are said to be characteristic 

 of the Tournaisian ; but in Great Britain and Ireland these shells are 

 found to have survived all through the deposition of the limestones, 

 being not at all rare in the upper beds. The fossils of the middle 

 zone are equally associated with those of the upper and lower in 

 British localities, while Productus giganteus and P. cora are by no 

 means confined to the upper beds. For example, P. giganteus occurs 

 at Hook Point in the Lower Limestones with Syringothyris cuspidatus, 



