Page:The Habitat of the Eurypterida.djvu/18

 described from the Utica shale of Holland Patent, New York (281), where one cephalic appendage and a portion of a thoracic somite were found. On the same piece of slate with these fragments Walcott found two characteristic Utica fossils, Leptobolus insignis and Triarthrus becki, and from the same locality comes a large graptolite fauna including Dendrograptus tenuiramosus, Climacograptus bicornis, as well as Schizocrania filosa and Endoceras proteiforme.

Lately there have been some extremely interesting discoveries of eurypterids in the Normanskill and Schenectady shales and sandstones (Black River and early Trenton age, respectively) of the Mohawk and Hudson valleys. Professor G. H. Chadwick has very recently found eurypterid remains in the sandstones of the Broom Street Quarry at Catskill, New York, in the Normanskill beds which until then had yielded only a graptolite fauna. Clarke and Ruedemann have described the species and also the beds from which they come. The eurypterids are very abundant in the sandstones though poorly preserved, but in the intercalated black shales, while less numerous they show better preservation. They are associated with graptolites and plant remains. Six species have been described by Clarke and Ruedemann. Eurypterus chadwicki, Eusarcus linguatus, Dolichopterus breviceps, Stylonurus modestus, Pterygotus ? (Eusarcus) nasutus, P. normanskillensis. Entire individuals are absent, the fauna being made up chiefly of carapaces.

The first profuse Upper Ordovicic fauna is found in the Schenectady shales (Trenton age), originally referred to the Frankfort. A preliminary notice of these specimens which appeared in 1910 (38, 31) shows that these remains "usually in fragmentary condition, abound most freely in fine-grained black shale, intercalated between thick calcareous sandstone beds. . . . . but they also occur in the sandy passage beds between the two. The sandy shales are full of organic remains, partly of the supposed seaweed Sphenothallus (Sphenophycus) latifolium Hall and partly of what appear to be large unidentified patches of eurypterid integument. In the black shales the eurypterid remains are rarer, but their surface sculpture is excellently retained, and here their organic associates are Climacograptus typicalis and Triarthrus becki. As a result of imperfect retention of these eurypterids in the rocks where they most abound and their sparseness in the shales which have best preserved them, we are still left in ignorance of the full composition of the assemblage, but it is safe to say genera, species and individuals were abundant at this early