EXPLANATION OF PLATE XXIII. 



HETEROPORA PARVICELLA (Gabb and Horn), p. 327 



1-2. Views of two fragments of zoaria, (x3). 



Vincentown lime sand; Vincentown, (154). 



RETELEA OVAUS Gabb and Horn, p. 328 



3. View of a fragment of a zoarium, natural size. 



4. View of a celluliferous surface, much enlarged. (Both fig- 



ures after Gabb and Horn.) 

 Vincentown lime sand. 



FLUSTREIXA ? CAPISTRATA Gabb and Horn, p. 329 



5. View of a fragment of a zoarium, much enlarged. 



6. View of the basal expansion, much enlarged, described as 



Membranipora dbortiva by Gabb and Horn. (Both fig- 

 ures after Gabb and Horn). 

 Vincentown Hmcsand. 



ONYCHOCEU,A DIGITATA (Morton), p. 330 



7-10. Views of four fragments of zoaria, (x2). 



Vincentown Hmcsand; Vincentown, (154}. 



BIFLUSTRA TORTA Gabb and Horn, p. 331 



11-12. Views of two fragments of zoaria, (x3). 



Vincentown Hmcsand; Vincentown, (154}. 



BIFLUSTRA DISJUNCTA Gabb and Horn, p. 333 



13. View of the celluliferous surface of a zoarium much en- 



larged. (After Gabb and Horn.) 

 Vincentown Hmcsand. 



AMPHIBLESTRUM HETEROPORA (Gabb and Horn) , p. 333 



14. Surface of zoarium, much enlarged. (After Gabb and 



Horn.) 



Vincentown limesand. 



15. Surface of a zoarium from the Eocene, (xao): (After Mary- 



land Geological Survey.) 



16. View of a single zoecium more highly magnified. (After 



Maryland Geological Survey.) 



MEMBRANIPORA PLEBIA Gabb and Horn, p. 334 



17. Surface of zoarium much enlarged. (After Gabb and Horn.) 

 Vincentown limesand. 



MEMBRANIPORA ANNULOIDEA Ulrich and Bassler n. sp., p. 335 



18. Surface of the zoarium, (x24). 



- Vincentown limesand; Vincentown, (154). 



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