688 PROCEEDINGS OF THE "BALTIMORE MEETING 



some of the echinoid material can not be with certainty determined. Among 

 the known Oligocene genera of the South Atlantic and Gulf areas are Cidaris, 

 Sismondia, Laganum, Amblypygus, Oligopygus, Cassidulus, and Eupatagus. 

 The great majority of the forms come from Florida. The Oligocene deposits 

 of California have also furnished specimens of Cidaris. 



The Miocene deposits of both the Atlantic and Pacific coasts have afforded a 

 considerable number of echinoderms, chiefly echinoids. The Atlantic Coast 

 Miocene contains Ophioderma (?), Cidaris, Ccelopleurus, Psammechinus, 

 Scutella, Encope, Mcllita, Agassizia, Brissus, Plagionatus, and Echinocardium. 

 The Pacific Coast Miocene, on the other hand, has furnished Asterias, Am- 

 phiura, Cidaris, Scutella, Clypeaster (?), Astrodapsis, and Linthia. 



The Pliocene deposits contain very few echinoderms. On the South Atlantic 

 coast from the Carolinas southward a few forms have been recognized, among 

 them Strongylocentrotus, Encope, and Clypeaster. On the Pacific coast Astro- 

 dapsis, Scutella, and Schizaster (?) are found. The Miocene and Pliocene 

 echinoids of the Pacific coast have been found to be of more than ordinary 

 value in the determination of geologic horizons. This is due to their limited 

 geologic range and to the fact that, where present at all, they are usually 

 abundant and well preserved. 



The Pleistocene deposits likewise have furnished very few echinoderms, and 

 those for the most part of species living in the adjacent seas. Among those 

 recognized from the Atlantic border have been Asterias, Aster acanthion, 

 Strongylocentrotus, Mellita, Moira, and Taxopneustes. On the Pacific coast, 

 on the other hand, several species of Strongylocentrotus and Scutella are 

 found. 



The paper was discussed by John M. Clarke and W. B. Clark. 

 The next paper read was 



AGE OF THE GASPEfi SANDSTONE* 

 BY HENRY SHALER WILLIAMS 



Contents 



Page 

 Former explanation of mixture of Hamiltonian and Oriskanian species in fauna of 



Gaspe sandstone (York River beds) 688 



Reasons for reviewing former interpretation 689 



Summary of evidence 693 



Conclusions 694 



Discussion 695 



Remarks by Cbarles Scbucbert 695 



Remarks by Jobn M. Clarke ^ 696 



Remarks by H. S. Williams 697 



Former Explanation of Mixture of Hamiltonian and Oriskanian Species 



in fauna of gaspe sandstone (york rlver beds) 



In a recent report by the State Geologist of New York 1 the invertebrate 

 fauna from the lower part of the Gaspe sandstone is described as having a 

 remarkable combination of two faunas, the species of which are generally 

 regarded as characteristic of the Oriskany and Hamilton formations respect- 

 ively. 



* Manuscript received by the Secretary of the Society January 8, 1909. 



1 J. M. Clarke : Early Devonic history of New York and eastern America, 1908. 



