LONSDALE ON MIOCENE CORALS FROM N. AMERICA. 505 



regular in outline, but which might be considered, in that con- 

 dition, as an oral aperture. In the perfectly closed cells, near the 

 base of the inverted cone, a slightly concave and apparently solid 

 lamina, occupied the whole surface. A careful study of the 

 general characters dependent upon the mode of forming this outer 

 layer will, it is believed, be found of service in establishing 

 specific differences among Lunulites, equal to that derivable 

 from the variable manner of producing the equivalent portion 

 in Escharce and Escharince. 



In the concave surface, the point of chief interest was the irre- 

 gular thickenings, connected, it is believed, with renewals of 

 growth, a feature of common occurrence in quincuncial species, 

 but not yet observed by the describer in those with parallel cells, 

 although M. Michelin has delineated carefully an apparently 

 analogous structure in Lun. urceolata. (Icon. Zoophyt. pi. 46. f. 6. 

 1845.) Where the renewed growth was supposed to have com- 

 menced, a layer, of animal origin, extended backwards from the 

 previous margin, and coated irregularly the anterior concave sur- 

 face, but with a clear separating line. In other species, which 

 permitted, on account of duplicate specimens, an examination to 

 be made, the thickening layer was easily detached, and its surface 

 was found to be impressed with the structure of that to which it 

 had been added, and without any blending of materials ; never- 

 theless, the layer differed not in the arrangement of its component 

 materials (an apparently vertical fibrous or laminated structure) 

 from that which immediately underlaid it, or was directly connected 

 with cells, and secreted by the polypes which occupied them. 



Locality. — Williamsburg. 



7. Cellepora informata. (Sp. n.) 



Incrusting, compressed globular or irregularly botryoidal cells, form variable, 

 surface densely porous ; mouth circular or oval, in same plane with surface, 

 margin raised, thickened, at proximal edge a narrow plate notched in the cen- 

 tre ; gemmuliferous (?) chamber, on one side of proximal margin of mouth ; 

 walls of cells separable ; vertically fractured section irregularly columnar ; con- 

 necting foramina near base of walls. 



This coral and the next were referred to Cellepora, on account 

 of the irregular manner in which the cells were aggregated, and of 

 the want of uniformity as respected the general surface of the oral 

 terminations ; in the situation of the chambers assumed to be 

 destined for maturing the gemmules there was also an agreement, 

 as well as in the absence of all marked changes dependent on 

 extreme age, with Cellepora pumicosa, and allied recent or extinct 

 species. Both fossils, however, presented the peculiarity of the 

 walls of the cells readily separating, and each portion of a fractured 

 specimen exhibited constantly flat, glossy, apparently solid 

 walls, totally unlike the curved surfaces occasionally obtained in 

 fractured sections of Cell, pumicosa : in the characters of the 

 mouth, in its being in the same plane with the surface, however 



