62 The Middle Devonian Deposits of Maryland 



bluish, sliglitly arenaceons and coarser shales, very near the northern end 

 of the cut, fossils are abundant, esi)eciallv 2' rop idol opt us carinatus (Con- 

 rad) numerous large and beautifully preserved specimens of which were 

 collected. Some of the other most abundant species are Spirifer mucro- 

 natus (Conrad), Clionetcs coronatus (Conrad), Chonetes setiger (Hall), 

 Chonetes mucronatns Hall, and Palaeoneilo constricta (Conrad). The 

 complete fauna of this zone is as follows : Spirophyton sp., Lingula ligea 

 (?) TLall, Stropheodonta (Leptostrophia) perplana (Convad), Stropheo- 

 donta (Douvillina) inaequistriaia (?) (Conrad), Orthotlietes variabilis 

 Prosser, Chonetes mucronatus Hall, Chonetes coronatus (Conrad), Chon- 

 etes scitul us Hall, Chonetes setiger (Hall), Chonetes lepidus Hall, Chon- 

 etes marylandicus Prosser, Camarotoechia prolifica (?) Hall, Tropido- 

 leptns carinatus (Conrad) (numerous large and beautifully preserved 

 specimens), Spirifer mucronatus (Conrad), Spirifer granulosus (Con- 

 rad) (pustules nicely preserved), Spirifer angustus Hall, Athyris spiri- 

 feroides (Eaton), Grammysia circuiaris (?) Hall (imperfectly preserved 

 specimen), Nucula hellistriata (Conrad), Nuculites triqueter Conrad, 

 Palaeoneilo constricta (Conrad), Palaeoneilo emarginata (Conrad), 

 Palaeoneilo tenuistriata ( ?) Hall, Mytilarca (Plethomytilus) oviformis 

 (Conrad), Actinopteria decussata (?) Hall (the concentric lines are not 

 as strong as in most of the specimens of this species), Avicuhpecten ( ?) 

 sp., Aviculopeclen princcps (?) (Conrad), Cypricardrlla hellistriata 

 (Conrad), Cypricardinia indcnta (Conrad), Bellerophon sp., Cyrtolites 

 (CyrtoneUa) mitella (?) Hall, Phacops rana (Green), Crinoid stems. 



It will be seen from the above list that this fauna is characteristic of 

 the Hamilton stage in New York, while the shales themselves, in litho- 

 logical characters are not different from many of the fossiliferous Ham- 

 ilton shales of that state. The exposures in this cut furnish an excellent 

 illustration of the upper Marcellus siiales. and the lower part of the fossil- 

 iferous Hamilton shales. The black, fissile shales at the southern end con- 

 taining specimens of Liorliynchus limitare (Vanuxem) are very similar to 

 typical outcrops of the ]\Iarcellus shale in New York, even to the rusty color 

 when weatliered and the calcareous concretions. Again, the succeeding 

 zone of more arenaceous shales with some thin sandstones in which fossils 

 occur rather infrequently is similar to the lower part of the Hamilton 



