10 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 1, 



A transverse section was taken from about the middle of the large 

 tooth, and exhibited the usual labyrinthic structure : rather less 

 complex than in the Labyrinthodon Salamandroides. 



The character of the exterior surface of the cranium was indicated 

 in the specimen originally submitted to me by the impression it had 

 left on the coal, when that substance was plastic : some of the 

 present fragments show the surface itself, and demonstrate the pitted 

 reticulate character which is so common in the Labyrinthodonts. 



All the additional evidence thus derived corroborates the inference 

 from the first portion of the present fossil skull, that it belonged to 

 a Labyrinthodont Reptile. 



A. On a Specimen o/^Nummulitic ^ocvifrom the neighbourhood 

 0/ Varna. By W. J. Hamilton, Esq., Pres. G.S. 



In offering to the Society the accompanying specimen of Nummu- 

 litic Limestone from Buyuk Aladyn in the neighbourhood of Varna, 

 I am desirous of making one or two observations respecting its oc- 

 currence. The specimen was forwarded to me by my brother. Col. 

 F. W. Hamilton, Grenadier Guards, who, in a first communication 

 (since published in the Literary Gazette, July 29, 1854, p. 690), ex- 

 pressed an opinion that the hollow depressions which occur abun- 

 dantly on the surface of these limestone hills were the result of arti- 

 ficial excavations, and that the columnar-looking rocks which remain 

 standing in the middle, were the pillars by which the roof was originally 

 supported. In a subsequent letter he observes that the hollow de- 

 pressions occur in so many parts of the country on the limestone 

 plateau, that he believes he must give up his former opinion that 

 they are artificial, and look upon them as natural depressions. 



On referring to Bone's *Esquisse Geologique de la Turquie 

 d' Europe' (Paris 1840), I find that, after mentioning the fact of 

 the vast development of the cretaceous formations in Turkey (p. 17), 

 he alludes to the occurrence in Bulgaria of enormous masses of Or- 

 bit olites, constituting a portion of the nummulitic group. Further 

 on (p. 21), he observes that the upper beds of these cretaceous rocks 

 are full of OrbitoliteSj to which he has given the name of O. Bul- 

 garica. 



He also alludes to the great prevalence of caverns and grottos in 

 some portions of the cretaceous beds of Turkey in Europe, many of 

 which have assumed the form and appearance of a funnel (ew^o/i- 

 noir). He believes them to be all natural, and to be owing to the dif- 

 ferent degrees of hardness of the different beds of rock. Some are 

 described as occurring on the surface of the plateau, probably re- 

 sembling, though on a smaller scale, those seen in the Carst near 

 Trieste. 



I have placed on the table for the purpose of comparison, a speci- 

 men of Nummulitic Rock from the centre of Asia Minor. I obtained 



