DESCRIPTIONS OF SPECIES. 119 



Milne-Edwards and Haime considered this species and their Astrolielia 

 'lesueuri as Miocene, but the Tertiary of Walnut Hills is well known to 

 belong' to the Vicksburgian Oligocene of Conrad, Dall, etc.^ 



Notes on Conrad's type, in the collection of the Academy of Natural Sciences of Philadelphia. Coill'ad 



has described a young branch that does not show the characters of the adult 

 specimens well. The calices are prominent and the corallites are more 

 inclined to the axis of the colony than is usual. 



Mm. 



Greater diameter of corallite at base 5 



Greater diameter of corallite at calice 4 



Lesser diameter of corallite at base 4 



Lesser diameter of corallite at calice 3. 75 



Height of corallite (measured on side) 2. 5 



Oue corallite has a height of -l. 2 



The specimen is so much worn as not to permit the surface ornamen- 

 tation to be made out well, but it is evidently of the type characterizing the 

 typical Oculina americana of Milne-Edwards and Haime. This species 

 presents an enormous amount of variation. The figures (PI. XI) show it 

 graphically. ^ From an inspection of the illustrations one would be inclined 

 to think there are no tangible specific characters, but there are several good 

 ones. The septa are very thin, and neither pali nor paliform teeth are well 

 developed. Because of the latter fact I have doubted whether the species 

 should be referred to Oculina. The other specific distinction lies in the 

 character of the coenenchymal surface. This is usually thrown into humps 

 or folds, especially around the bases of the projecting portion of the 

 corallites; and it is covered by wavy, often disconnected, striae. The striae 

 are almost concentric around the basis of the* free part of the corallites. 

 The coenenchymal surface in Oculina vickshurgensis is more regular, the 

 striae are more continuous, and usually follow a g-eneral longitudinal course 

 quite closely. These features are indicated by the figures. 



' See Conrad, Am. Jour. Sci., 2d ser., Vol. II, 1846, p. 210. 



