132 EOCENE AND LOWER OLIGOCENE CORAL FAUNAS. 



STYLOPHORA rONDEROSA sp. IIOV. 

 PI. Xiri, fig. IG; PI. XIV, figs. 1 to 11). 



Cdralluiu, subplane or rounded masses, the largest of an irregular form, 

 40 cm. across and 10 cm. thick. Calices shallow, small, crowded; diameter, 

 1 mm.; distance ai)art, 0.5 nmi. The cojnenchymal surface is preserved in 

 its original condition on none of the numerous specimens in the United States 

 National Museum; therefore its character must be deduced from the sec- 

 tions parallel to the long axes of the corallites. As shown by PI. XIII, fig. 16, 

 the ccEuencliyma is laminate. PI. XIV, fig. lb, represents a portion of the 

 weathei'ed surface of a specimen seen in longitudinal section; PL XIII, fig. 1 6, 

 is a magnified, thin, longitudinal section. In the former figure the laminae 

 are seen to be joined to each other liy vertical elevations, while the latter 

 figure shows light-colored laminae, with tall sjiines of the same material. 

 The higher lamina may rest on the spines (or echiuulations) of the lower, or 

 the spines may not quite reach from the lower to the next higher lamina. 

 The spaces intervening between the laminte and spines are filled by darker 

 material. 



It is extremely difficult to determine exactly how iiiucli of the orig-inal 

 structure has been completely obliterate<l. In the instances where the spines 

 do not reach from the lower to the next sujjei-imposed lamina, we may have 

 a secondary condition, brought about by chemical changes in the corallum. 

 In some ])laces in the thin section the white calcite can be seen passing grad- 

 ually into the darker, more amorphous material. 



The following probably represents tlie original character of the crenen- 

 chyma: Coenenchyma, laminate, surface covered by tall erect spines (echinu- 

 lations); each succeeding lamina in general rests on the summits of the 

 echiuulations of the immediateh' preceding lamina. 



Septa, six well developed, reaching the columella ; (juite often rudi- 

 ments of a second cycle can be distinguished, but only the first cycle is 

 well developed; they are thicker at the wall. The usual ap])earance of 

 the specimens is to have no septa at all, they having been destroyed in the 

 process of fossilization. Dissepiments are present, but their details could 

 not be made out. The corallite cavities usually are filled with solid 

 calcite or are rotted out and hollow. The columella is moderately stout 

 and styliform. 



