PLATE LXXXVII— Continued 



Myiilarca fibristkiata. 



Page '26*. 

 See Plate 33. 

 Fig. H. The left valve tig. 6, plate 33, redrawn to show the true form of the anteiior side. This species is 

 the only radiate form of the genus yet described and more perfect material may show 

 charactei-s which would exclude it from Mytilarca. 

 Yellow sandstone. Burlington, Iowa. 



Mvrii,.\i{f"A oinBOSA. 



Pago 'i63. 

 See Plate 33. 

 Fig. 7. The left valve fig. 20, plate 33, redrawn to show more clearly the entire form of the valve. 

 Chemung group. Napoli, Caltaraugus\Co., N. T. 



Mytilarca (PLExuojiyriLus) omformis. 



Page 255. 

 See Plate 31. 

 Fig. 8. The upper portion of a right valve showing tho. oblique po.stenor teeth of the hinge. 

 Hamilton group. York, Limngslon Co., N. T. 



MoDioLA (Mytilop.s) METELLA. 



P-ige 2G8. 

 See Plate 33. 

 Fi". 9. A right valvi' showing the form and proportions of the shell. 

 Chemung group. Warren, Pa. 



Myhlarca (Pi,ethomytilus) arenacea. 



Pago 253. 

 See Plate 30. 

 Fig. 10. A left valve. 



Schoharie grit. Schoharie, N. Y. 



Mytilarca Occident a lis. 



Page 263. 

 See Plate 33. 



Fig. 11. The left valve fig. f>, plate 33, redrawn to show the form of the beak and anterior side. The 

 outlines of this one and of fig. 6 are partially restored from other specimens and represent all 

 that can be determined from the imperfect material. 

 Yellow sandstone. Burlington, Lrwa. 



GOSSELETTIA TRIQUETRA. 

 Page 26.1. 

 See Plate 31. 

 Fig. 12. A large right valve of elongate form. 



Hamilton group. Fidtonham, Schoharie Co., N. Y. 



Mytilarca (Pletiiomytilus) Knappi. 



Page 256. 

 Fig. 13. The right valve described, .showing the form of the shell and the striated ligamental area. 

 Hamilton group. SkaneaUles lake, N. Y. 



