88 PROCEEDINGS OF THE GEOLOGICAL SOCIETY, [Juiie 14, 



tioiial means for transmitting support and calcareous matter through- 

 out the whole of the living portion of the polype. From the foregoing 

 statements it is inferred, that the narrow crested lamellae are only the 

 perfect external state of the broad-rihbed casts, and that the lamellse 

 are strictly cellular bodies. A notice on the composition of that 

 structure generally would occupy very many pages ; but attention 

 may be called to three different examples. In an appendix to Sir 

 K. I. Murchison's work on the Geology of Russia*, instances of a 

 bi-plated composition are mentioned ; INIr. Dana alludes to hollow 

 lamella? in his description o^ Ast. OrbiceUa curtaf ; and Prof. Gold- 

 fuss, in his delineations of the Astrcea explanata of Count Munster|:, 

 exhibits a curiously catenated character. The intimate construction 

 of lamellse deserves the careful study of competent physiologists, and 

 it is conceived that it will be found of great value in attempting to 

 establish generic and specific distinctions. 



The plan of producing additional cavities for digestive organs re- 

 mains to be noticed. Respecting marginal developments, no satis- 

 factory cases were observed of immature states ,- the bounrlaries oi 

 the lateral extensions presenting a smooth, solid edge (iig. 12), indi- 

 cative of the animal having been impeded in its operations, and having 

 completed its structures previous to death. Some of these visceral 

 hollows v/ere also small, as if sufficient room had not been afforded 

 for a normal construction ; one of the characteristics of such cavities 

 being an area of full or mature dimensions at every stage af formation, 

 whenever adequate space exists. Of young interpolations many ex- 

 amples were noticed. The Red Hill cutting specimen afforded a 

 good instance of an early, but not the first condition (fig. 14). It 

 was surrounded by mature hollows ; the form was almost quadrangu- 

 lar, the width about half a line ; and the lamellse, so far as could be 

 ascertained, — some having been broken, — had been equally developed 

 on all sides, with indications of four projecting beyond the rest. Near 

 that case was another rather more advanced, the size being greater 

 and the lamellae moi*e numerous. Many similar productions occurred 

 in the same specimen as well as among the broad Atherfield casts 

 (fig. 12), allowance being made for different states of preservation. 

 In all cases the relative degree of development was about equal around 

 the interior of the young cavity ; and the adjacent mature hollows 

 did not display any defect on the side next the interpolation ; whereas 

 in fissiparous processes the lamellse in early stages are rudimentary 

 along the line of partition, as respects both the parent and the severed 

 offspring, but elsewhere, in each case, of fall dimensions. Twin pro- 

 ductions were not uncommon. They resembled a long incipient hol- 

 low divided about the middle, each cavity being similar in size and 



* Vol. i. App. A., art. Sliflastrcea inconferta, p. G21-62?, 1845. Count Key- 

 serling in his wo.k on the Petschoia-Land, dissents from the bi-])]ated structutes 

 mentioned in the notice of that coral; but the author begs to adliere to his ori- 

 ginal statement (Wissenschaftliche Beobachtungen auf einer Reise in das Petschora- 

 Land, p. 153, 1845). 



t Exploring Expedition, Zoophvtes, p. 209-210 ; consult also p. 53, 1846. 



I Petrefacten, vol, i. p. 112, pi. "38. fig. 14 a,h. 



