MARYLAND GEOLOGICAL SURVEY 137 



The fauna of this zone, as represented just north of the Maryland 

 state line, contains 15 described species, six of which are characteristic 

 Lowville fossils and the rest Black Eiver forms. The gastropods Helico- 

 toma planulatoides Ulrich and Omospira alexandra (Billings) are par- 

 ticularly characteristic species of the upper Lowville, but the coral 

 Tetradium cellulosum, found everywhere, is the best guide fossil. The 

 list of species discovered by Ulrich in this bed in southern Pennsylvania 

 a few miles north of the Maryland line is as follows. Only traces of the 

 Louisville rocks and faunas can be found in Maryland and for that reason 

 only the fifteen specifically identified faunas of this list are described. 



Fauna of the Tetradium cellulosum Bed, Chambersburg Limestone 







Camarocladia rugosum Ulrich 



Beatricea sp. 



Streptelasma profundum (Conrad) 



Tetradium cellulosum (Hall) 



Clieiocrinus sp. 



Orbignyella wetherbyi (Ulrich) 



Strophomena cf. 8. emaciata 



Zygospira recurvirostris (Hall) 



Protorhyncha sp. 



Ctenodonta gibberula Salter 



Cyrtodonta sp. . . 



Helicotoma planulatoides Ulrich 



Helicotoma verticalis Ulrich 



Lophospira cf. L. procera 



Omospira alexandra (Billings) 



Clathrospira sp. 



Eunema cf. E. salteri. 



Orthoceras sp. 



Leper ditia fabulites (Conrad) 



Leperditella tumida (Ulrich) 



Isochilina cf. 7. gracilis 



Isochilina cf. I. Ottawa 



Macronotella ulrichi Ruedemann 



Drepanella macra Ulrich 



Aparchites sp. 



Primitia so. 



Kloedenia sp. 



Isotelus sp. 



Pterygometopus callicephalus (Hall) 



Ceraurus pleurexanthemus Green 



