60 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 19, 



in Me7topoma and Menobranchus* (fig. 10). Prof. Quekett has also 

 found similar batrachian structure in the small vertebree above alluded 

 to. (See PI. III. fig. 9.) 



In breaking up the rock in which the reptilian remains were im- 

 bedded. Dr. Wyman found another fossil body, which he and Sir C. 

 Lyell immediately suspected to be a Land-Shell allied to Pupa or 

 Clausilia, having the central whorls larger than the anterior and pos- 

 terior ones, and exhibiting the same kind of striation as characterizes 

 the shells of these pulmoniferous mollusks. Dr. Gould, of Boston, 

 detached the same fossil more completely from the matrix (see PI. IV. 

 figs. 1, 2, 3, 4) ; but he was unable to discover the mouth, so as to 

 enable a conchologist to determine the genus with precision. He ob- 

 served that in its form and striation it bore no resemblance to any 

 known marine shell. M. Deshayes, when the fossil was shown to 

 him, declared at once his opinion that it was the shell of a pulmoni- 

 ferous and terrestrial mollusk, of the same family as that to which 

 Helix and Pupa belong. 



[Doubts, however, having been expressed by other palaeontologists 

 (since this paper was read) as to the correctness of this conclusion, 

 the specimen was submitted to Prof. Quekett for microscopical exa- 

 mination. Part of the striated or finely grooved surface, on being 

 magnified 50 diameters (see PI. IV. fig. 5), presented exactly the 

 same appearance as a portion, corresponding in size, of the surface of 

 the common Ym^i^ Pupa juniperi (see PI. IV. fig. 6). On making 

 sections of such parts of the fossil shell as were not in too crystalline 

 a condition to exhibit structure. Prof. Quekett detected the same 

 prismatic or hexagonal tissue and the same tubular structure as are 

 generally characteristic of the shells of mollusca, and as may be 

 seen in the recent Pupa, P. juniperi, before alluded to. See PI. IV. 

 figs. 7-14. One of the sections, moreover, exhibited what may pro- 

 bably have been a portion of the columella and spire somewhat 

 crushed (PI. IV. fig. 7, upper part), for, as will be seen by the 

 magnified representation of the entire shell (PI. IV. figs. 2-4), it had 

 been svibjected to considerable pressure, and had been slightly flat- 

 tened and fractured. — March 21, 1853.] 



More than usual hesitation has been felt in acceding to the con- 

 clusion that this fossil belonged to the family Helicidce, inasmuch as 

 no land-shell had previously been observed in any palaeozoic rock ; 

 but the mode of occurrence of this body appears in perfect accord- 

 ance with the idea of its being referable to a pulmoniferous mollusk, 

 since it was lying among the rotten wood in the interior of a hollow 

 tree, the upper part of which doubtlessly projected into the air 8 or 

 9 feet above the roots, or into the water during river inundations. 



In connexion with the reptilian remains, it may not be irrelevant 

 to observe, that Mr. Logan and Dr. Harding have previously called 

 attention to the foot-prints of a quadruped imprinted on sandy slabs, 



* In a plate of the volume of the Histological Catalogue, Mus. Coll. Surg., on 

 which Prof. Quekett is now engaged, sections of the hones of recent Batrachians 

 are magnified on a uniform scale, namely 440 diameters, and the identity of size 

 and character of the hone-cells can at once be recognized. 



