﻿Vol. 6 1.] SEQUENCE IN THE BKISTOL AREA. 279 



LlTHOSTROTION IRREGULARE (Phill.). 



Here I include : — 



Lithostrotion irregulare, Edwards & Haime, ' Monogi*. Brit. Foss Cor ' 



pt. iii (1852) p. 198 & pi. xli, figs. 1-1 e. 

 Petalaxis Portlocki , Edwards & Haime, ibid. p. 204 & pi. xxxviii, 



figs. 4-4 a. 



I include the last-named coral, on the evidence of specimens 

 which appear to be merely forms wherein the corallites of Litho- 

 strotion irregulare are very closely packed. 



Since it is customary to refer any narrow dendroid Lithostrotion 

 to this species, and since no horizontal section has been figured by 

 Edwards & Haime, I append the following detailed account of the 

 structure which I connote by the specific name : — 



(1) The corallites are narrow and closely packed, in parallel 



grouping. 



(2) In a horizontal section, the two walls are usually in contact, 



but when they are separate, the space between them is only 

 divided up by the two series of septa. 



(3) In a horizontal section, a certain number of the larger septa 



extend to the columella, and the columella is usually con- 

 tinuous, in the direction of its length, with two of the larger 

 septa, so that the section appears to be bisected. 



(4) The tabulae are close-set and conical, so that, in a horizontal 



section, the central area exhibits a simple Clisiophyllid- 

 structure. 



Lithostrotion jtjnceum (Mem.). 



As interpreted by Edwards & Haime, ' Monogr. Brit. Foss. Cor.' pt. iii 

 (1852) p. 196 & pi. xl, figs. 1-1 b. 



The Nematopliylluxn-Section. 



Corallites prismatic, forming a compact mass. 



Lithostrotion basaltieorme (Phill.). 



As interpreted by Edwards & Haime, ' Monogr. Brit. Foss. Cor.' pt. iii 

 (1852) p. 190 & pi. xxxviii, figs. 3-3 b. 



A very common Bristol variety is described in Proc. Bristol Nat. 

 Soc. n. s. vol. x (1903) pp. 106-108. 



The Group of Lithostrotion Portlocki (Bronn). 



Here I include : — 



Lithostrotion Portlocki, Edwards & Haime, 'Monogr. Brit. Foss. Cor.' 



pt. iii (1852) p. 194 & pi. xlii, figs. l-\g. 

 L. ensifer, Edwards & Haime, ibid. p. 193 & pi. xxxviii, figs. 2-2 a. 

 L. M'Coyanum, Edwards & Haime, ibid. p. 195 & pi. xlii, figs. 2-2 b. 



For descriptions, see Proc. Bristol Nat. Soc. n. s. vol. x (1903) 

 pp. 108-10. 



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