14 THE HABITAT OF THE ETJRYPTERIDA 



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 Tri- 

 arthrus becki, and from the same locality comes a large graptolite 

 fauna including Dendrograptus tenuiramosus , Climacograptus bicornis, 

 as well as Schizomania filosa and Endoceras proteiforme. 



Lately there have been some extremely interesting discoveries of 

 eurypterids in the Normanskill and Schenectady shales and sand- 

 stones (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 Ruede- 

 mann 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 Schenec- 

 tady shales (Trenton age), originally referred to the Frankfort. A 

 preliminary notice of these specimens which appeared in iqio (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 (Sphe- 

 nophycus) latifolium Hall and partly of what appear to be large uni- 

 dentified 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 



