870 



NEW YORK STATE MUSEUM 



spent by D. D. Luther in the office on this work. They are now 

 in the hands of the engraver, and it is hoped that they will soon 

 be available. 



The fauna of the pyrite layer at the horizon of the Tully limestone. 



I reported last year that an investigation of this subject was 

 under way, and I am gratified to be able to incorporate the 

 results of this work in this report. The work has been carried 

 forward at my suggestion by Dr F. B. Loomis, assistant pro- 

 fessor of biology at Amherst College. Its interest lies in the 

 fact that we have here to deal with conditions influencing or- 

 ganic associations at the sea bottom, which can be interpreted 

 only by actual experiment or from the most careful results of 

 recent investigations on the varying conditions in existing bodies 

 of salt water. Certain factors prevailing during Paleozoic time 

 have brought about a segregation of iron sulfid in the sea water, 

 which has deposited itself in an almost continuous sheet over a 

 distance of 100 miles along the edge from Canandaigua 

 lake to Lake Erie. With it are involved multitudes of 

 organic remains, all of them of extraordinarily diminutive 

 size and yet, as Dr Loomis has shown, representing ar- 

 rested and primitive phases of the profuse fauna which occu- 

 pied the ground before these peculiar conditions set in. This 

 important fact being determined, namely that the fossils are 

 only modified stages or conditions of the organisms which pre- 

 vailed in that sea, the theorem is to demonstrate the character 

 of the sea which could produce such a deposit. It has been 

 usual to regard black bituminous shales, which generally carry 

 large quantities of such pyrite deposits, as indicative of shallow 

 or foul waters where decomposition has gone on with so much 

 freedom as to produce directly much carbonate of iron and thus 

 indirectly the sulfid. It is not however certain that we are cor- 

 rect in a conclusion of this kind, as recent studies of confined 

 bodies of sea water, for example the Black sea, have indicated 

 that separation of the sulfid is largely due to bacteria acting 

 on the animal remains, but this is a process which takes place 

 in the great depths where the bottom is covered with black mud, 

 so that by comparison, such pyrite deposits, together with the 

 black bituminous shales with which they are usually associated, 



