424 The Upper Devonian Deposits of Maryland 



These divisions are paleontological in the Maryland region and are 

 mapped as a unit, since they have not been differentiated lithologically. 

 It is not improbable, however, that they may be discriminated in the 

 future when the names Sherburne and Ithaca would be appropriate be- 

 cause of their close resemblance to those members of the Portage forma- 

 tion of New York. 



Beds Containing the Naples Fauna. — A list of the species observed in 

 this zone in Maryland has been given on a preceding page. All are 

 characteristic of the Naples fauna which occurs in the Sherburne mem- 

 ber of the Portage of New York. Fossils are rare in these beds in both 

 areas. 



The Maryland strata also resemble the Sherburne beds lithologically, 

 consisting of alternating fissile, olive-green shale and flaggy sandstones, 

 while they occupy a like stratigraphic position in both states. The 

 vertical range of the faunas is similar in both sections. The resem- 

 blance of this division to the Sherburne of New York is thus so close as to 

 indicate their essential identity. 



Beds Containing the Ithaca Fauna. — The upper division of the Wood- 

 mont member closely resemhles the underlying strata lithologically, but 

 contains a very distinct fauna characterized at most localities by the 

 abundant occurrence of Spirifer mucronatus var. posterns, Productella 

 speciosa, Pugnax pugnns var. altus, Schizophoria striaiula, Cyrtina 

 liamiltonensis, and Liorhynchvs glohuliforme. The table of distribution 

 lists the species observed in this zone in Maryland and gives their occur- 

 rence elsewhere. 



Seven of these species, Spirifer mucroiwtus var. posterns, Productella 

 speciosa, Cyrtina haniiltonensis, Atrypa reticularis, Spirifer mesistrialis, 

 Actinopteria cf. boydi, and Palceoneilo constricta are placed by Williams 

 among the dominant species of the Ithaca fauna.' Pugnax pugnus var. 

 alius and Schizophoria striatula are also prominent members of that 

 fauna. One of the species, Pterinea chemungensis, is said by Williams ' 



'Bull. U. S. Geol. Survey, No. 210, p. 74, 1903. 

 ' Journal of Geology, vol. xv, p. 98, 1907. 



