PLATE LXVI—Continued. 
SpHENOTUS ? ARCUATUS. 
Page 400. 
Fig. 18. A cast of a right valve, showing the anterior muscular impression and pieserving the remains of 
striae of growth. 
Chemung- group. Near Panama, N. Y. 
SPHENOTUS FLAVIUS. 
Page 103. 
Figs. 27-29. Left, right and cardinal views of a specimen which has been somewhat compressed vertically. 
Waverly group. Licking Co., Ohio. 
SPHENOTUS VALVULUS. 
. Page 403. 
Fig. 30. A right valve. 
Waverly group. Newark, Ohio. 
Sphenotus -ZEolus. 
Page 404. 
Figs. 31-34. A series of right and left valves showing some variety of form and aspect. 
Waverly group. Ohio. 
Fig. 35. A cardinal view of the specimen fig. 33, showing the long ligamental area. 
Waverly group. Licking Co., Ohio. 
Spatiiella typica. 
Page 407. 
Figs. 36-40. Left and right valves showing variation in form and proportions. 
Chemung group. Tompkins and Chemung Co's. N. Y. 
Spathella VENTRICOSA. 
Page 408. 
Figs. 41, 42. Two left valves. 
Burlington sandstone. Burlington, Iowa. 
Sphenotus arcalformis. 
Page 395. 
See Plates 65, 76. 
Fig. 43. A left valve, referred with doubt to this species. 
Chemung group. Near Smethport, Pa. 
