53 351 Renoselceria mutabilis Hall, Upper Shell limestone Lower Helderberg group. Beecraft's Mt. Hudson, N. Y. 352 Grammysia bisulcata Conrad Hamilton group. Pratt's Falls, N. Y. 353 Modiomorpha mytiloides, Conrad Hamilton group. Pratt's Falls, N. Y. 354 Modiomorpha concentrica, Conrad, Hamilton group. Pratt's Falls, N. Y. 355 Tentaiculites gyracanthus, Eaton. Tentaiculte limestone Lower Helderberg group. Clarksville, N. Y. 356 Pentaculites gyracanthus, Eaton. Tentaicuite limestone Lower Helderberg group. Clarksville, N. Y. 357 Spirifera vanuxemi, Hall. Tentaiculte limestone Lower Helderberg group. Clarksville, N. Y. 358 Cyrtoceras n. sp. Shaly limestone Lower Helderberg group. Clarksville N. Y. 359 Acidaspis tuberculata, Con. Shaly limestone Lower Helderberg group. Clarksville, N. Y. 360 Acidaspis tuberculata, Con. Shaly limestone Lower Helderberg group. Clarksville, N. Y. 361 Acidaspis tuberculata, Con. Shaly limestone Lower Helderberg group. Clarksville N. Y. 362 Acidaspis tuberculata, Con. Shaly limestone Lower Helderberg group. Clarksville, N. Y. 363 Acidaspis tuberculata, Con. Shaly limestone Lower Helderberg group. Clarksville, N. Y. 364 Acidaspis tuberculata Con. and Acidaspis hamata, Con. Shaly limestone Lower Helderberg group. Clarksville, N. Y.