142 THE CAMBRIAN AND ORDOVICIAN DEPOSITS OF MARYLAND 



Carabocrinus sp. (plates) 



Porocrinus sp. 



*Diplotrypa appalachia Bassler 



Stromatotrypa sp. 



Mesotrypa f sp. 



Stictoporella ? sp. 



*Prasopora contigua Ulrich 



Hemiphragma cf. irrasum 



*Corynotrypa inflata (Hall) 



*Corynotrypa delicatula (James) 



*OrtMs tricenaria Conrad 



Plectorthis aff. P. whitfieldi 



Dalmanella testudinaria var. 



Pianodema cf. P. subaequata 



*Scenidium anthonense Sardeson 



Strophomena cf. 8. ftlitexta 



Rafinesquina cf. R. incrassata 



Leptaena sp. 



Plectambonites cf. P. pisum 



Plectambonites sp. 



Triplecia (Cliftonia) simulatrix Bassler 



Leperditia cf. L. Jabulites 



Ampyx cf. A.-normalis 



Illaenus sp. 



Pterygometopus cf. P. callicephalus 



*Ceraurus pleurexanthemus Green 



*0nchometopus simplex Raymond and Narraway 



Christiania Bed. This division of the Chambersburg limestone is best 

 developed on the east side of the Martinsburg shale belt in southern 

 Pennsylvania where it reaches a maximum thickness of 270 feet. West 

 of the shale belt it is absent from the section, but going southwestward 

 into Maryland this division reappears and gradually increases in thick- 

 ness until northern Virginia is reached, where it is 40 feet thick. The 

 prevailing rock of this division is thin bedded, shaly limestone and cal- 

 careous shale sometimes quite fossiliferous. The brachiopod Christiania 

 trentonensis is the most characteristic of the described species and speci- 

 mens may usually be found at its outcrops. In Pennsylvania outcrops of 

 the Christiania bed have yielded a fauna of over 40 species which indi- 

 cates that the age of the division is latest Black Eiver or earliest Tren- 

 ton. The list of species, identified by Ulrich, is given below. As this bed 

 is so poorly represented in Maryland only its more characteristic fossils 

 are described in this volume. 



