BUFFALO SOCIETY OF NATURAL SCIENCES 6 1 



marine, Grabau in favor of the non-marine. The Water lime forma- 

 tion was particularly under discussion, but though many arguments 

 were brought up on both sides, neither was able to convince the 

 other. 



In the June number of the Bulletin of the Geological Society of 

 America (191 1) Clarke writing, on the "Relation of the Palaeozoic 

 Arthropods to the Strand-Line," speaks of the size of the eyes of 

 eurypterids and crustaceans as indications of the depth of water in 

 which the forms lived. It was formerly supposed that crustaceans 

 with large eyes had acquired them by adaptation to great depth of 

 water. Clarke cites the case of a trilobite with enormous compound 

 eyes living among many Cambric forms wholly devoid of lenses, and 

 other examples of a contradictory character, so that the size of the 

 eye cannot be taken as proof of either deep or shallow water, but 

 rather implies that the complex, highly-specialized eyes of certain 

 forms enables these individuals better to adapt themselves to either 

 deep or shallow water conditions. Clarke reiterates the opinion that 

 "the few early eurypterids we know were doubtless marine, and the 

 creatures gradually acquired the brackish-water habit of their climax, 

 which seems to have eventually changed to a fresh-water life" (37, 

 280). 



In 1 91 2 the most recent contribution to the study of North Ameri- 

 can eurypterids was made in Clarke and Ruedemann's Monograph on 

 the Eurypterida of New York (39). While the work has to do mainly 

 with the description of species and the study of larval stages and of 

 the anatomy, leading to fuller knowledge of the ontogeny and phy- 

 logeny of the eurypterids as well as their taxonomic relations, still 

 the authors have given some attention to the question of the bionomy 

 (39, 96-113), coming to the following conclusions: 



"Summarizing these data we conclude that the eurypterids lived 

 in the sea from Cambric to Siluric time. They had then become 

 less sensitive to changes, positive and negative, in the salinity of 

 the water. In fact they seem to have thrived best under conditions 

 of life that excluded most other marine groups of animals, that is, 

 in the marginal, more or less inclosed marine lagoons, accompanied 

 by estuaries receiving delta-forming terrestrial drainage, with pre- 

 vailing arid or sub-arid climate, the waters being in some places more 

 than normally briny, in others having less than normal salinity. In 

 other words they were euryhaline or able to live in both salt and 

 brackish water. 



