true Carboniferous Nummulite. 229 



the type has reverted to its primitive state, gradually dwindling 

 in size, and losing by degrees those minor characters which 

 were the easily recognized evidence of higher organization, 

 and in its later history suggesting the lingering stages which 

 precede complete extinction. 



It has been already stated that one of the Nummulites de- 

 scribed by Fraas from the Cretaceous beds of Palestine is 

 named N. variolaria^ var. lyrhna^ and that Dr. Glimbel's ob- 

 jection to its being accepted as a Cretaceous representative of 

 the genus 'appears to be grounded solely on its supposed 

 zoological affinity. The discovery of a form so similar, in 

 rocks of a still earlier period, appears to render such an ob- 

 jection untenable unless otherwise supported. 



Locality and Geological Position. — The localit\^ whence the 

 material containing the specimens above described was ob- 

 tained is a Carboniferous-Limestone quarry near Xamur — 

 " la Carrih-e du Fond d^Arquet " — the exact geological rela- 

 tions of which will be best understood by a brief abstract of 

 particulars, furnished to me by M. Yanden Broeck. 



The Carboniferous Limestone of Belgium is divided by 

 !M. Dupont into six sets of beds, which have been named from 

 the localities in which they are respectively best developed. 

 They are as follows, beginning at the lowest : — des Ecaussines^ 

 de Dinantj d^Anseremme, de Vaulsor^ de Namnr^ and de Vise. 

 The section at the Cam^re du Fond d'Arquet belongs to the 

 top but one of these divisions, which is described as a black 

 dolomitic limestone with large Euomphali — black and compact 

 at the base, and dolomitic in the upper portion, the charac- 

 teristic fossils being Euomphalus cequalis and E. acutiis. 

 The material collected was from three distinct bands of marly 

 calcareous shale near the base of the section. Two out of 

 the three contained examples of the Nummulite, though the 

 number of specimens was exceedingly small in proportion to 

 the quantity of material, and, owing to the nature of the matrix, 

 almost all of them were more or less broken. 



It may be well to mention that a single Nummulite of the 

 same species has been found in a packet of greyish limestone 

 d(5bris from Flemalle near Liege, wliich, geologically, pertains 

 to the uppermost of the divisions above quoted — that of 

 " Vis^ ;" but until further specimens have been obtained from 

 the same horizon, this second locality must be regarded as 

 requiring confirmation. 



It only remains for me to express my grateful acknowledg- 

 ments to ^r. Ernest Yanden Broeck of Brussels, to whom I 

 am indebted for the material in which tins interesting little 

 Nummulite has been found. To the pains he has taken to 

 verify every particular as to the exact position of the beds in 



