502 A. W. GKABAU PALEOZOIC DELTA DEPOSITS OF NORTH AMERICA 



moner generic designations. These remains in the Frankfort [Sche- 

 nectady] shale are distributed through fully 1,500 feet of strata off a 

 northeast-southwest coastline in an area of maximum deposition." 98 



Eleven species have been described from the fragmentary material of 

 the Schenectady shale, all of them new. They belong to the genera 

 Eurypterus, Eusarcus, Dolichopterus, Hughmilleria, Pterygotns, and 

 Stylonurus ?. The material consists mainly of cephala, carapaces, and 

 fragments of legs and abdominal segments. Rarely are a few abdominal 

 segments attached to the carapace, while specimens containing parts of 

 legs attached are extremely rare. Xo complete specimen has been found, 

 the most perfect one being a carapace, with one swimming leg attached 

 and six abdominal segments. This specimen is also partly macerated.* 

 Typical Frankfort material has not yet been recorded, but we may expect 

 to find it at any time. 



Still more recently Eurypterid remains have been discovered by Prof. 

 G. H. Chadwick in sandstones of the Xormanskill horizon at Catskill, 

 Xew York : 



"The lithological and faunal conditions at the Broom Street quarry expo- 

 sures [where these remains were found] were found to he a singularly complete 

 duplication of those of the Eurypterid-hearing exposures in the Milestone 

 quarries at Schenectady. The Broom Street quarry is also a bluestone quarry, 

 the rock being mostly used in the crusher. The courses of 'bluestone' (here 

 an impure argillaceous sandstone) are very compact, from 3 to 30 feet thick 

 between the intercalations of black shales. There is distinct evidence of 

 shallow-water conditions, .one bed being conglomeratic and largely composed 

 of pebbles, many of which appear to be mud pebbles : another beautifully 

 exhibiting very regular, widely separated wave marks with winnows of com- 

 minuted seaweeds and eurypterids in the troughs. 



"Quite as in the bluestone quarries of the Schenectady beds, the surfaces of 

 some of the sandstones are densely covered with rather poorly preserved sea- 

 weeds and eurypterids. It was therefore natural to expect that here too the 

 black intercalated shales would contain better material of these fossils and 

 possibly also graptolites that would indicate the age of the beds. They have 

 indeed afforded a layer with an association of finely preserved seaweeds, the 

 eurypterids herewith described, and the following graptolites: Dicelloffraptus 

 guarleyi Lapworth. Climdcograptus bicornis Hall. Climacograptus bicornis var. 

 pcltifcr Lapworth. Cryptograptus tricorms (Carruthers), the first three in 

 great abundance. This graptolite association is one of undoubted Xormanskill 

 age. The seaweeds occur in large perfect fronds and are of the same type as 

 those in the Schenectady shale. The Eurypterids also are strikingly similar to 

 those from the Schenectady beds." " 



08 Bull. 149. N. Y. State Museum. 1011. pp. 30. 31. 

 * See plate 85, figure 13, Memoir 14. N. Y. State Museum, part ii. 



1,11 Memoir 14, N. Y. State Museum : The Eurypterids of New York, by John M. Clarke 

 and R. Ruedemann. pp. 411-412. 



