BUFFALO SOCIETY OF NATURAL SCIENCES , 63 



plain deposits and in deltas" (87, 989). For further references on 

 this subject in the Principles see pp. 377, 425, 945, 950, 1029, 1030. 



This gives us, then, the last word on the subject up to the present 

 time. Looking over the opinions which have been recorded in the 

 preceding pages, one is struck with the diversity of conclusions ar- 

 rived at by our greatest American geologists and by not a few of those 

 of Europe. From 1818, when the first Eurypterus was found, though 

 it was not described as such till 1825, down to the end of the century, 

 it was practically a universal opinion that the eurypterids had been 

 denizens of the sea. The species were described along with marine 

 forms and were considered to have been marine also. The study of 

 the taxonomic position of the Eurypterida, showing always more and 

 more clearly their close relationship to the modern Kingcrab, Limu- 

 lus, gave an added reason for assuming a marine habitat for the fos- 

 sil forms. With the beginning of the present century came the awak- 

 ening of geologists and paleontologists to the fact that perhaps these 

 extinct Merostomata had not always lived in the sea, that they may 

 even never have known marine conditions. The current opinion now 

 is that the eurypterids lived in the sea from Pre-Cambric time through 

 the Ordovicic. During the Siluric they gradually became adapted 

 to brackish and fresh-water conditions, living in estuaries and lagoons 

 in the Devonic and becoming entirely fresh -water habitants in the 

 Mississippic, Carbonic and Permic. Grabau is the only staunch advo- 

 cate of the non-marine habitat even from the earliest times, though 

 Chamberlin, to be sure, has argued such a possibility, but his discus- 

 sion is purely philosophical, and while interesting and full of sugges- 

 tive ideas, it is, nevertheless, unsupported by the evidence necessary 

 for definite proof of his theory. 



In attacking this problem the most important thing to determine 

 is whether the Eurypterida began their existence in the sea or in the 

 land waters, and under what conditions they lived in pre-Devonic 

 time, for after that, it is now generally conceded, they lived in ter- 

 restrial waters. 



