BUFFALO SOCIETY OF NATURAL SCIENCES 1 93 



discovered in these beds plant remains related to Psilophyton, and a 

 fish which Traquair describes as Cephalaspis lornensis (Macconochie 

 157, Traquair 273). 



Geikie calls our attention to what is believed to be "the oldest 

 lacustrine or fluviatile mollusk yet known, Amnigenia (Anodonta, 

 Archanodon) jukesii. This shell has been found in the Upper Old 

 Red Sandstone of Ireland and England, associated with land-plants, 

 (Archaeopteris, Sphenopteris, Bothrodendron, Ulodendron, Stigmaria 

 Calamites) fishes (Coccosteus) and arthropods (Eurypterus). 



12. MISCELLANEOUS OCCURRENCES 



We have now completed the discussion of the significance of the 

 eleven most important eurypterid faunas, the ones which it has seemed 

 to the writer offered the most material from which to draw deduc- 

 tions. In addition there is a certain group of occurrences which 

 appear to be able to throw little light upon the determination of the 

 habitat, and they have not been discussed so far, for, if from the best 

 material which we have at hand it can be proved that the eurypterids 

 lived in the rivers from the very beginning of their history, then we 

 need be no more distressed at finding a fragment among marine 

 remains than we are when we find a single leaf or piece of wood asso- 

 ciated with brachiopods and molluscs. But, lest the advocates of the 

 early marine habitat of the eurypterids should complain that I pass 

 over lightly the very cases which seem to prove conclusively to them 

 that their view is correct, I shall take up those cases briefly and show 

 wherein they do not prove what they are supposed to; but rather if 

 of any weight at all, indicate that the eurypterids did not always live 

 where their remains were entombed. These remaining instances, 

 then, fall into three groups. 



(1) The presence of a single eurypterid fragment or perhaps two 

 or three fragments associated in the same stratum with a typical, 

 well preserved, marine fauna. 



(2) The presence of a single eurypterid fragment or complete 

 individual in a stratum barren of other fossils, but immediately pre- 

 ceded and succeeded by strata carrying marine fossils. 



(3) The presence of quite a number of fragments in scattered 

 occurrence, but associated intimately with a typical marine fauna. 



To the first group belong the following: 



Echinognathus clevelandi, Utica shale, Upper Ordovicic. 



