60 STANLEY SMITH. 



The measurements given for the particular "species" are 

 averages or means, the selection of which lias been made 

 according to the principle of priority. 



In any scheme of classification ultimately adopted, the 

 non-columate forms should for general convenience retain 

 in some form or another, the specific name by which they 

 are known as well as that, of the columate species to which 

 they belong, e.g., Diphyphyllum late sept atam M'Ooy — 

 non-columate "forma" of L. irregulare large variety, and 

 of L. martini small variety. 



Distribution. 



Lithostrotion is the most prolific genus of the rugose 

 class found in the British Carboniferous sequence, but has 

 a limited range, namely, the Visean, i.e., the higher part 

 of the Lower Carboniferous. Within the particular zones 

 it occupies, it occurs very abundantly, forming in many 

 places vast coral growths incorporated in the limestones 

 or covered by calcareous shales. It is, I believe, equally 

 abundant in Belgium 1 and I have examined specimens from 

 several localities in Russia. It has been recorded and 

 described from Eastern Asia 2 and also from North America, 3 

 but none of the American forms which I myself have 

 examined, 4 appear to be congeneric with the British types. 

 I do not wish to imply that true Lithostrotion may not 

 have been found within that continent. 



I have been informed by Mr. J. Coggin Brown of the 

 Indian Geological Survey that the genus has not yet been 

 recorded in any of the publications of that body. 



1 Arthur Vaughan. Correlation of the Dinantian and Avonian. Q.J. 

 G.S., 1915, Vol. lxxi, pp. 1 - 52. 



2 Yabe Hisakatsu and Hayasaka Ichiro; Palaeozoic Corals from Japan, 

 Korea and China: Journ. Geol. Soc. of Tokyo, Vol. xxn, pp. 93 - 109, and 

 pp. 127-142 (1915). These authors described some species as from the 

 Permian. 



3 Citations too numerous to quote. 



* Specimens in the British Museum South Kensington, and examples 

 kindly sent to me by Dr. G. H. Girty of the U.S.A. Geological Survey. 



