DISTRIBUTION AND OCCURRENCE OF EURYPTERIDS 513 



states that the conditions above the oolite were those of dry land. In the 

 southeast of Gotland, at the Lau Canal, the oolite is represented by a 

 Pterygotus-bearing marl. Thus in Oesel and Gotland the Eurypterid 

 beds are nowhere typically marine, but always of a peculiar nature, either 

 lagoon or else along lines of break marking a change of conditions from 

 marine to non-marine or vice versa. Moreover, the Eurypterids are al- 

 ways found associated with scorpions. In Galicia and Podolia extensions 

 of the Oesel zone occur, with a few remains of the Eurypterids. A single 

 fragment of Pterygotus has been reported from the Upper Siluric of 

 Australia. 



Devonic. — With the Devonic throughout the world comes a sudden 

 drop in the number of remains found. There are 95 species in the Si- 

 luric, as compared with 17 in the Devonic. There is no doubt that the 

 Old Eed sandstone of Great Britain is non-marine, even though in Eussia 

 and north Germany it grades into marine beds. In the lower part of the 

 Old Eed are found eight species of Eurypterids, all associated with fresh- 

 water fish and plant remains. With the exception of the three Ptery- 

 gotus species, there are only fragments found. Pterygotus anglicus forms 

 a notable exception, for there are numerous well preserved specimens of 

 this species, which ranges in length up to 5 or 6 feet and is always asso- 

 ciated with the Old Eed fishes. A few fragments of Eurypterus hiberni- 

 cus Baily have been reported from Ireland in the Upper Old Eed asso- 

 ciated with land plants (Archoeopteris, Sphenopteris, etcetera), fishes, and 

 a nuviatile or lacustrine mollusk, Amnigenia jukesii. In the Upper De- 

 vonic sandstones of Condroz, Belgium, Eurypterus lohesti Dewalque and 

 E. ? dewalquei Fraipont are found associated with animals and land- 

 plant remains. 



In North America the pure marine sediments of Devonic age, deposited 

 in the very places where in Bertie time the water-lime was deposited, do 

 not carry a single Eurypterid, while in the Siluric there had been an 

 ever increasing number of species and of individuals, giving a total of 36 

 species for the whole period. In the Devonic, on the other hand, there 

 are few representatives in the Lower and Middle Devonic of the interior 

 region, and it is not until the top of the Upper Devonic thai those re- 

 mains are found again in numbers. The American representatives of 

 the Lower "Old Eed," the Gaspe sandstone and related formations of 

 Campbellton and Dalhousie, New Brunswick, have furnished fragmentary 

 specimens of Pterygotus and other types. A fragment of Pterygotus has 

 been obtained from the Grande Greve limestone of the Lower Devonic o( 

 Gaspe. Fragments of P. atlanticus CI. and E. occur in the higher IV- 

 XXXV— Bull. Gbol. Soc. Am., Vol. 24, 1012 



