PLATE XLIII. 



(Figures 1-13 by P. B. Meek; 14, 15, 18-30 by R. P. Whitfield; 16, 17 by E. Emmons.) 



Genus MERISTELLA, Hall. 



Page 73. 



Meeistella arcuata, Hall. 

 See Plate 44. 

 Figs. 1, 2. Two views of a noi'mal shell ; showing form and contour. 



Lower Helderberg group (shaly limestone). The Helderbergs, N. Y. 



Meristella l^vis, Hall. 



See Plate 44. 

 Figs. 3-6. Dorsal, profile, cardinal and front views of an adult shell. 



Lower Helderberg group (shaly limestone). Albany county, N. Y. 



Meristella bella, Hall. 

 See Plate 44. 

 Figs. 7-9. Ventral, front and dorsal views of a normal individual ; showing the median sinus on both 

 valves. 



Lower Helderberg group. Schoharie, N. Y. 



Meristella peinceps, Hall. 



Figs. 10, 11. Profile and front views of an example of extremely large size, with an unusual development 



of the shallow median sinus and linguiform extension in front. 

 Figs. 12, 13. Dorsal and ventral views, presenting the usual characters of an adult specimen. 

 Lower Helderberg group. Schoharie, N. Y. 



Meristella subquadrata, Hall. 



Figs. 14, 15. Dorsal and profile views of a typical specimen. 



Lower Helderberg group. Schoharie, N. Y. 



Meristella Walcotti, sp. nov. 



See Plate 44. 



Figs. 16, 17. Dorsal and profile views of a rotund and rather elongate example. 

 Oriskany sandstone. Cayuga, Ontario. 



Meristella nasuta, Con rati. 



See Plate 44. 



Fig. 18. Ventral view of a shell of median size. 



Corniferous limestone. Erie county, N. Y. 

 Figs. 19, 20. Dorsal and profile views of an unusually large, strongly nasute example ; showing in profile 

 the plano-convex contour of the shell. This is the form originally described as Meristella 

 Elissa, Hall. 



Schoharie grit. Albany county, N. Y. 



Meristella Doris, Hall. 

 Figs. 21, 22. Dorsal and profile views of a normal shell ; showing the deltidial plates and fine radial surface 



striae. 



Corniferous limestone. Williainsville, N. Y. 



