106 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



In transversal sections there are both large and small tubes ad- 

 jacent to the median lamella, because the tubes are thin at their 

 base, but the gemmation appears still as triparietal, because in dorsal 

 gemmation there are only small tubes adjacent to the basal lamella. 



D E 



Fig. 29. Cliilopora guernoni Haiiue, 1854. 

 A, B. The bilamellar zoarium natural size and the surface enlarged (after 

 Haune). 



C. Tangential section, X 16. 



D. Portion of a meridian section, X 16. 



E. Transverse section, X 16, showing the median lamella. 



F. Longitudinal section, X 16. 



Jurassic (Bathoniau) : Occaigues (Orne), France. 



Occurrence. — Jurassic (Bathonian) : Ranville, and Occaignes, 

 France. 



Plesioti/pe.—Canu collection and Cat. No. 68954, U.S.N.M. 



CHILOPORA CRETACEA, new species. 



Plate 17, fig.s. 14-16. 



DescHption. — The zoarium is free, formed of compressed, bi- 

 lamellar fronds, bifurcated, with peripheral growth. The tubes are 

 cylindrical, short, with triparietal gemmation on a slightly thick- 

 ened basal lamella ; they are terminated exteriorly by a salient and 

 triangular superior lip. The ovicell is globular or convex, smooth, 

 quite small. The mesopores are very short and parietal. 



Structure. — Without the ovicell, the occurrence of a Cliilopora 

 in the Cretaceous would have been unperceived; indeed this same 



