198 



OirrHOTHKTEs AKCTosTRiAins. Hall. ( Fig. 1)0.) ( Pal. 

 N.Y., Vol. IT., p. 71, PI. IX.) 



Bistinguishino' Cbarafters. — Hinge line equal to or greater 

 than the width of tlie shell, seldom less; sides of the shell 

 rectangular to the hinge line, or curving inward from it ; 

 surface striae closely arranged. 



Fig. 96. Orthothetes arctostriatiis. Two bracbical valves and an enlargement of the sui-- 

 faoe strife (from Hall). 



Found in the upper part of the Moscow shales, Sections 2 

 and 3 (rare) ; in the low^er Moscow shale, five feet above the 

 Encrinal limestone. Stictopora 

 and Demissa beds, at Section '^^ ~ 

 5; between one and three feet 'j|^ 

 below the Encrinal limestone, \F' 

 at Section 6 (common ) ; below 

 three feet, at Section 6 (spar- 

 ingly); from seven to twelve ^.. 



feet below the Encrinal lime- .• f 



if 



stone, at Section 7 (common); £ 

 below twelve feet, at Sections 7 ►- 

 and 8 (sparinglv). Also found %. 



m the Trilobite beds, at Sec- ^W', ; " 



tion 8 (rare) ; between the Trilo- ^' ...,,, au-' 



bite and Strojjhalosia beds, on 

 the Lake Shore and in Avery's ■ - 



Creek (commcm); in the Transi- 

 tion beds, on the Lake Shore 

 (rare). 

 Orthothetes p e r v e r s u s . . - •"■ "''^ 



Hall. (Fig. 1)7.) (Pal.N.Y.,Yol. Fig.QT OrthoUutc.pevversusBv^- 

 ^ ^ ' ^ 111. ^^ . J- ., » VI. p)^,^j valve: internal mold of large 



TV lA TO T>1 ! V \ brachial valve; pedicle valve (from 



i-\ ., p. <-, 1 1. i.V.j jjaii) 



