62 THE HABITAT OF THE EURYPTERIDA 



"Their adaptation to such conditions is paralleled today by such 

 crustaceans as Apus and Artemia which not only thrive under rapid 

 diminution of normal salinity but, by means of strongly protected 

 eggs, even survive salt pan conditions which end in complete desic- 

 cation, as shown by their well known occurrence in desert lakes. 

 The usual associates of the Siluric eurypterids are peculiar crusta- 

 ceans whose nature emphasizes the reference above made. They are 

 phyllocarids and ostracods and members of the strange family Hemi- 

 aspidae (Neolimulus, Bunodes, Hemiaspis, Pseudoniscus) . This con- 

 geries of peculiar crustaceans seems to constitute a fauna especially 

 adapted to, and therefore highly characteristic of, lagoon and estuary 

 conditions. 



"Thus while the earlier eurypterids were marine and their cli- 

 macteric fauna euryhaline; their later habit throughout the Devonic 

 and Carbonic led them finally into the fresh water. 



"The succession of habitats is hence, according to our evidence, 

 the reverse of that suggested by Chamberlin's hypothesis noted at 

 the beginning of this discussion" (39, 112, 113). 



In 1913 appeared the first extensive discussion of the habitat of 

 the eurypterids in a paper entitled "Early Palaeozoic Delta Depos- 

 its of North America" by Professor Grabau, in which he brings 

 forward arguments for the fluviatile habitat of these meros tomes in 

 the Ordovicic and Siluric of North America, and he includes a sum- 

 mary of the distribution and occurrence of the eurypterids by myself, 

 reviewing the evidence and coming to the conclusion that the euryp- 

 terids were river-living at least during the two periods mentioned. 

 The significance of the occurrences in the Pittsford, Shawangunk, 

 and Bertie are discussed especially. 



At the end of the same year Grabau 's Principles of Stratigraphy 

 was published. In Chapter XXVIII on the "Bionomic Character- 

 istics of Plants and Animals" and elsewhere in the book the euryp- 

 terids are spoken of as fluviatile organisms as indicated by their dis- 

 tribution, faunal associates and mode of occurrence. A single state- 

 ment taken from this book will show the position which Grabau holds. 

 " . . . . The early remains of fish as of eurypterids are not 

 found in normal marine deposits, but in those which are at least open 

 to the suspicion that they are formed by rivers or ac least at the 

 mouths of rivers, while the best preserved remains, and the most 

 abundantly represented in the Palaeozoic, are found in river flood- 



