MEMBRANIPORIDiE. 51 



The pevistome differs very remarkably in different specimens, as may be seen njjon com- 

 parison of lig. 7, PI. VI, with tig. 4, PI. XXII, though there can be no doubt of these 

 figures representing different conditions of one and the same species, as shown by the 

 existence of all intermediate forms in some part or another of the polyzoarium. 



{b) Without oral spineis. 

 21. L. rYRiFORMis (?) S. W. PL V, fig. 3. 



Cellulis elongato-ovatis sen pyriforniibus, umbonatis ; superficie obscure punctata sen 

 scrobiculata, longitudinaliter striatula. Orificio semicirculari, labio inferiori recto. Ovi- 

 cellula antice carinata, superficie integra. 



Cells elongato-ovate or pyriform ; surface obscurely punctate or dotted, with a fine 

 longitudinal striation ; a central unibonal projection ; orifice semicircular, straight below ; 

 ovicell keeled in front, obscurely punctured. 



LeP. GRANIPERA (?). 



Habitat. — C. Crag, 8. W., on various shells. 



This species, which appears to be that intended by Mr, S. Wood under the same 

 appellation, bears a strong general resemblance to the recent L. granifcra. The principal 

 differences between them being : that in the fossil there is no median pore a short distance 

 below the orifice, which is invariably present in Z. (jranifera, in which also the punctures 

 on the front of the cell are usually more confined to the marginal portions, and not 

 scattered uniformly over the surface. The characters in which the two forms agree are : 

 the form of the orifice, the general aspect and form of the cells and the longitudinal 

 striation of the surface, and the form, &c., of the ovicell, so that with the exception of 

 the median pore there seems to be every reason to conclude that the fossil and recent 

 forms should be placed together. But as I have not yet met with a specimen of 

 L. granifera in which that pore was absent, nor one of L. pgrifonuis in which it existed, 

 it is perhaps better to regard them as distinct though closely related. 



The lower border of the orifice in this species usually presents a denticulate appearance, 

 which is due apparently to a sort of crystallization of the carbonate of lime. 



