LOWER SILURIC SHALES OF THE MOHAWK VALLEY 5 1 



thin limestone band. The top is formed by a white hard sandstone 

 bank 3^ feet thick and consisting largely of rounded sand grains. 

 This is separated by shale, one layer of which consists of pyrite, 

 from an underlying gray sandstone bed, also composed of rounded 

 grains. The sandstone beds of this upper part of the formation are 

 extremely irregular courses; in one case a bed was seen to run out 

 within 10 feet from 4 feet to 5^ foot. 



These beds present an extremely barren aspect ; the only observa- 

 tion of fossils in them of which we are aware is that by Walcott 

 (title 17, page 345) who states: ''The only fossils I found at this 

 locality were Orthis testudinaria and T r i n u - 

 cleus concentricus." Very thorough search has 

 furnished us a small graptolite faunule in the shales of the lower 

 200 feet and another faunule in the thin calcareous sandstone inter- 

 calations of the second hundred feet. A few bands of the latter 

 proved to be covered with the remains of a microfauna, especially 

 small crinoid joints. 



The shale has furnished: 



Dictyonema arbuscula U I rich (r) 



Diplograptus peosta Hall (r) 



Dicranograptus nicholsoni Hopkinson (typical) (rr) 



The sandstone contains a pronounced microfauna which has been 

 kindly determined for us by Doctor Ulrich as follows: 



1 Columns and calyx plates of a cystid allied to 



Cheirocrinus (r) 



2 Very pentagonal columns 



3 Small Heterocrinus columns (cc) 



4 Callopora nealli (James) Ulrich 



5 Arthrostylus tenuis Ulrich 



6 Helopora n. sp. 



7 Rhinidictya cf. parallela (James) 



8 Rafinesquina ulrichi (James) (cc) 



9 Plectambonites nov. (=: centricarinatus nov.) (c) 



10 P. plicatellus (Ulrich) 



11 Dalmanella multisecta (Meek) (c) 



12 Lepidocoleus jamesi (Hall & Whitfield) (c) 



13 Ceratopsis chambersi (Miller) (typical) (c) 



14 Trinucleus bellulus Ulrich (c) 



15 Acidaspis crossota Locke (c) 



16 Calymmene (Cincinnati Eden species) 



We also had a Tentaculites cf. flexuosa Hall, 

 a small Hyolithes, fragments of C e r a u r u s p 1 e u r e x a n - 



