SELENARIID^S. 89 



in Cuvier and Brongniart (op. c.), whose figure is copied in Bronn (Syst. d. Urwelt. &c.), 

 and which is also represented in Michelin, ' Icon. Zooph.,' pi. xlvi, fig. G, and is doubtless 

 the form intended by Lamarck under the name of L. urceolata, though at first sight 

 differing very considerably from L. conica of Defrancc, on closer inspection proves, I 

 think, to be identical with it. The chief difference appears to consist in the truncated or 

 blunt summit and depressed form of L. urceolata, whilst in L. conica the summit is 

 usually more or less pointed. Not having had an opportunity of inspecting a specimen 

 of the Grignon fossil, and consequently in ignorance of the character of the posterior 

 surface, I cannot express a very decided opinion, but am strongly inclined, from the close 

 resemblance between the two in the disposition of the apertures of the cells and of the 

 vibracula in regular circles around the cone, to regard their identity as highly probable. 

 L. urceolata of Lamouroux is, as he himself observes, more properly a Citpitlaria, and is, 

 therefore, wholly out of the question, and it is very strange that it should have hitherto 

 been so generally cited as a synonym of L. urceolata, Lamarck. 



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