﻿1851.] 



LONSDALE ON GREENSAND CORALS. 



113 



Murchison's list, and I have figured and described it from his speci- 

 men, the only one found. The true generic position of it and the 

 next are very doubtful. I have dedicated it to Mr. J. De Carle 

 Sowerby, who drew up the catalogue quoted of the oolitic fossils of 

 the Hebrides. 



Potamomya 1 Sedgwickii. Plate V. fig. 3 a, 3 b. 



Shell transversely elongated, inequivalve ?, subcompressed, tumid 

 near the beaks, rounded at both ends, most produced and dilated an- 

 teally, marked by concentric furrows of growth. This evidently di- 

 stinct, yet, in the absence of better specimens, obscure shell, is the 

 " transversely elongated bivalve not yet named or figured," compared 

 with a Wealden shell, in Sir Roderick Murchison's list. I have 

 dedicated it to Professor Sedgwick, who jointly with Sir Roderick 

 Murchison examined the geology of Loch Staffin. 



January 22, 1851. 



Thomas Webster Rammell, Esq., and Robert Rawlinson, Esq., were 

 elected Fellows. 



The following communications were read : — 



1. Memorandum respecting Choristopetalum impar and Cya- 



THOPHORA? ELEGANS. By WlLLIAM LONSDALE, Esq., F.G.S. 



I. In the volume of the Palseontographical Society for 1850, M. Milne- 

 Edwards and M. Jules Haime state that Choristopetalum impar does 

 not appear to them to belong to the class Zoa?itharia, but is in their 

 opinion a Bryozoon* — the. grounds of dissent not being however 

 mentioned. When the description of the fossil, published in the 

 Quarterly Journal of the Geological Society f, was under preparation, 

 the author's attention was necessarily called to the class Bryozoa, in 

 consequence of the generic name Heteropora having been assigned to 

 some of the specimens previously to their coming into his possession ; 

 and it was not until all the detected structures had been carefully con- 

 sidered, that the fossil was referred to Zoantharia or Anthozoa. In 

 the description, the visceral receptacles are stated to be tubular, and 

 the tubes to be crossed at irregular levels in adjacent receptacles, by 

 transverse laminae or diaphragms J — 'tabulse' of M. M. -Edwards and 

 M. J. Haime; and these structures are carefully delineated by Mr. 

 J. de Carle Sowerby in plate 4. fig. 6'+, particularly as respects 



* Op. cit., Memoir on British Fossil Corals, p. 70. 

 t Vol. v. p. 66-77. 



% Loco citato, p. 66, 1. 22, 24 ; p. 68, 1. 12 from bottom et seq. ; p. 69, 1. 10 

 et seq. and 23; p. 70, 1. 17, also last line with continuation in p. 71 ; p. 71, 1. 32 

 et seq. 



