PLATE m— Continued. 



AVICULOPECTEN INSIGNIS. 

 Page 34. 

 See Plates 1 and 81. 

 13. The interior of a right valve imbedded in shale, showing the ornamentation as it appears on the 



interior of the shell. 



Hamilton group. Hamburg, Erie Co., IV. Y. 



AVICULOPECTEN ORNATUS. 

 Page 37. 

 See Plate 2. 

 Pig. 14. The interior of a left valve imbedded in shale, x 2. 



Hamilton group, Caiianilaii/tia lake, N. Y. 



AVICULOPECTEN HUCRONATUS. 

 Page 38. 

 Pig. 15. The interior of a left valve imbedded in shale. 



Hamilton group. Dresden, YatesiCo., N. Y. 



AVICULOPECTEN LAUTUS. 



Page 14. 



See Plate 81. 



Fig. 16. The interiorof two attached valves imbedded in shale, showing their comparative form and pro- 

 porti 



Hamilton group. West Bloomfield, N. Y. 

 Pig. 17. The interior of a left valve presen ed as the preceding. Another figure of this specimen is given 

 on plate 81, fig. 5, taken from an impression of this mould. 



Hamilton group. York Centre, Livingston Co'., N '. Y. 



A VICULOFECTEN EXACUTUS. 

 Page 8. 

 Fig. 18. The interior of a left valve imbedded in shale. 



Hamilton group. Hamburg, Erie Co., N. I'- 

 ll '. \ Bmall left valve with the anterior ear imperfect. 



Hamilton group. Ganandaigua lake, X. Y. 



Pig. live. The beak is represented as too acute, and tl acentric lamellae 



.are not shown as on the specimen. 



Hamilton group. Hamburg, Brit Co., N. )". 

 Pig. 21. A left valve denuded of the test. The specimen shows the pallial lino and muscular impression, 



as described in the text. 

 Fig. 22. The upper portion of a right valve preserving the test. 

 II [ton group. Hamburg, Erie Co., X. Y. 



