54 THE HABITAT OF THE EURYPTERIDA 



not Crustacea, but belong to the class Arachnida. The work has 

 only just begun of convincing that same geological world that the 

 habitat never was marine, but always fluviatile. 



For nearly fifty years after Conrad made his statement authors 

 described new species, erected new genera and worked out the affinities 

 of the eurypterids to Limulus, but they gave not a thought to the 

 habitat. It was not until 1889 that a direct reference was again made 

 to the habitat. In Nicholson and Lydekker's Manual of Paleontology 

 (196) we find the statement that "the nature of the deposits in which 

 the remains of the Eurypterids are found, and of the fossils asso- 

 ciated with them, would prove that these animals were essentially 

 marine, their habits, probably being very similar to those of the 

 existing King-crabs. It is, however, possible that certain of the 

 Eurypterids were inhabitants of brackish or even of purely fresh 

 waters" (196, 544). 



In 1893, Malcolm Laurie, studying the eurypterid remains in the 

 "Upper Silurian" of Scotland, i.e. the Siluric as generally used in 

 America, found in those rocks of the Pentland Hills only one other 

 fossil, Dictyocaris ramsayi, a crustacean (?) (144). The large eyes in 

 most of the eurypterids which he found caused him to think that they 

 must in some way be due to the conditions under which the creatures 

 lived, and from a comparison with recent forms he was led to believe 

 that the eurypterids lived in deep water, whether marine or not he 

 does not say, but the former seems to be implied. 



Amadeus W. Grabau writing in 1898 of the eurypterids said: 

 "these Crustacea were undoubtedly marine" (81, 362) thus accepting 

 the usual classification and also the current opinion as to the habitat. 

 On the other hand, Freeh (70) at about the same time, said that the 

 most evident proof of the retreat of the sea in the formation of the 

 Old Red sandstone in England was the appearance in the Devonic of 

 the eurypterids from the Baltic. This marks the beginning of the 

 change in ideas and embodies the first statement contrary to the pre- 

 vailing opinion that the habitat of the eurypterids was marine. 



The period during which it was either tacitly assumed or defi- 

 nitely stated that these extinct merostomes had lived in the sea was 

 thus brought to a close. There had been a few hints of a possible 

 non -marine existence, but on the whole geologists and palaeontolo- 

 gists had for eighty years been agreed upon the marine habitat. 



With the beginning of the new century we find a radical and 

 sudden change of opinion. Chamberlin in his paper on "The Habitat 



