202 



Found in the lower Moscow shale, at Sections 4 and 5 

 (common); p]ncrin;d limestone, at Section 5 (rare) ; between 

 the Ti-ilobite and Strophalosia beds, in Avery's Creek, and 

 on the Lake Shore (rare). 



Chonetes setkjerus. (Hall.) (Fi,o\ 1(J7.) (J'al. X. Y., 

 Vol. IV.,]). 129, IM. XXI.) 



Jh'stin_ii-nis]jinL> Characters. — Sf nii-elliptic;d 

 outline; moderate convexity ; moderate num- 

 ber of rounded surface stria? and vertical 

 seMger]^' Yenu-&\ Cardinal spiues, of which three occur on each 



valve.x2,fromHalI,. ^-^^ ^^. ^he beak. 



Found in the Hamilton shales, at Section G, two to three 

 feet below the Fncrinal limestone (vei-y rare); seventeen to 

 twenty-one feet below the Encrinal, at Section 7 (rare); 

 Pleurodictyum beds, in Avery's Creek (occasionally); Transi- 

 tion shales and Marcellus shales, in Lake Shore Cliffs (not 

 very common ). 



Cho.netes scm-Lrs. Hall. ( Fio. 108.1 (Pal. X. Y., Vol. 



IV., p. 130, n. XXI.) 



Distinguishing C/iararfe/N.— Semi-oval outline; somewhat 

 gibbous character; numerous surface stride; nnmerous cardi- 

 nal spines (as many as twelve or fourteen being sometimes 



Fig. 108. Chonetes scihdus. Ventral fpedicle) and dorsal (braehiaU views of a speci- 

 men, natural size ; interior of pedicle and of brachial valves, enlarged (from Hall). 



indicated), which pass ol)li(juely outward; interior of bra- 

 chial valve strongly pustulose, with a broad depression along 

 the center, from which rises a slender median ridge; a similar 

 median ridge occurs in the interior of the pedicle valve. 



Found in the lower two feet of the Moscow shales, at Sec- 

 tions 4 and 5 (rare); in the Encrinal limestone (rare); 

 throughout the Lower (Hamilton) shales, at Sections 5, 6, 7, 

 <S, and on the Lake Shore, and in Avery's Creek (often abun- 

 dant); Transition shales, on the Lake Shore (rare). 



