1 68 NORTH AMERICAN INDEX FOSSILS. 



166. C. dumosa Urich. (Fig. 217, c.) Eocenic. 

 A bushy mass of frequently and irregularly dividing and coa- 

 lescing branches 1.5 to 3.0 mm. thick ; surface with maculae slightly 

 depressed, smooth or with mesopores ; gonocysts large rounded or 

 irregular inflations; axial hollow 0.2 to 0.4 mm., with partitions 

 incomplete. 



Aquia formation of Maryland. 



CI. Ceriopora Goldfuss. 



Encrusting, massy, lobate, or ramose often in two or more 

 superposed layers of tubes; tubes, of one kind, subequal, in close 

 contact with amalgamated porous walls; apertures round or poly- 

 gonal over entire upper surface. 



Abundant in Alpine Trias, less so in Jura, common in Cretacic; 

 Tert. 



167. C. micropora Goldfuss. (Fig. 217, d.) Eocenic. 

 Depressed globular, hollow beneath ; apertures polygonal varia- 

 ble in size. 



Nanjemoy formation of Maryland. 



CII. Heteropora Blainville. 

 Generally ramose, sometimes of several layers of tubes ; aper- 

 tures rounded, with raised peristomes ; mesopores numerous, angu- 

 lar, usually completely surrounding the zocecia or in clusters, their 

 orifices closed in perfect specimens. Structure as in Ceriopora. 

 Jurar-Cret., abundant and Tert.-Recent rare. 



168. H. parvicella Gabb and Horn. Cret.-Miocenic. 

 Branches round, irregular, often anastomosing, of several layers 



of cellules ; apertures subregularly disposed with numerous round 

 mesopores, and marked peristomes. 

 Upper Cretacic of New Jersey. 



169. H. tortilis Lonsdale. Miocenic. 

 Apertures placed irregularly, with large irregular angular meso- 

 pores and thin walls. 



Miocenic of Virginia and South Carolina. 



Order CHILOSTOMATA Busk. 

 OIL Biflustra d'Orbigny. 

 Colony lamellose or ramose, cellules on sides in longitudinal 

 series, with slightly elevated peristomes, the anterior position partly 





