THE EURYPTERIDA OF NEW YORK III 
were prevailingly inhabitants of the brackish water zone, and in Devonic 
time they were wholly so. 
In the Carbonic era on this continent the eurypterids are mainly per- 
petuated by the peculiar subgenus Anthraconectes, in the Productive Coal 
Measures. These are found in Pennsylvania on slabs densely covered with 
fern leaves and other plant remains which can not fail to suggest near land 
and probable fresh-water conditions. Yet even in this case, the fragmen- 
tary condition of many of the fern leaves which would, according to the 
criteria of the ‘‘Allochthonie”’ of the coal measures, advanced by Potonié: 
indicate the transported condition of the material; even more the profuse 
presence of the small spiral tubes of the marine Spirorbis on the plant 
remains, as shown by Simpson’s excellent figure [Hall, 1884, pl. 6] afford a 
caution against an unqualified conclusion as to the fresh-water habit of these 
Carbonic eurypterids. Ina recent exhaustive discussion, Girty? has reached 
the conclusion that it seems’ most reasonable to regard the fauna of the 
¢ 
Carbonic of Pennsylvania “as a natural assemblage of species selected and 
modified by a habitat, if not in strictly marine, at least not in strictly fresh 
waters.’ | 
There is, however, clear evidence at hand of the fresh-water habitat 
of the Carbonic eurypterids in other regions. One of these is the occurrence 
of Eurypterus (Adelophthalmus) granosus Jordan in 
the coal measures of Saarbricken. That basin was formed in the interior 
of a continent and never reached by the sea.*- In other coal basins, notably 
those of England‘ the gradual freshening of the lagoons and the disap- 
pearance of such marine types as Lingula and Orbiculoidea, which are 
frequent in the lower coal measures, has been clearly recognized. It is 
only in the upper measures that the eurypterids occur, there in association 
with ostracods, phyllopods and schizopod crustaceans. Woodward [1879, 
1Frech. Lethaea Geognostica. 1899, pt 1, v. 2, no. 2, p. 270. 
2Jour. Geol. rg0g9. 17:309. 
*Frech. op. cit. p. 270. 
*Geikie, Text-book of Geology. 2: 1031. 
