554 E. W. Shuler — New Ordovician Eurypterid. 



latus in recognition of the very pronounced development of 

 the alveolar processes surrounding the spines. 



The endognathites figured above are in many respects simi- 

 lar to those figured by Clarke and Ruedemann (N. Y. State 

 Museum Memoir 14, 19L2, Yol 2, p. 541) under the name 

 Stylonurus (Cte?iopterus) multispinosus. This species pos- 

 sesses elongated joints fringed with spines along the posterior 

 margin. While there is a difference in the general shape of 

 the joints the chief distinction between the species multispino- 

 sus and alveolatus is in the prominent development of the 

 alveolar process and the unusual size of the distal spine in the 

 specimen from the Bays sandstone. Stylonurus {Ctenopterus) 

 multispinosus Clarke and Ruedemann occurs in the Pittsford 

 shale of the Middle Silurian. It is interesting to find an 

 Ordovician species so strikingly similar to a form which comes 

 from a much higher horizon in the Silurian. 



Dr. Bassler and others have correlated the Bays sandstone 

 with the Lorraine of New York. Dr. A. W. Grabau has made 

 it the equivalent of the late Maysville and Richmond. The 

 general character of the fossils collected with the Eurypterid 

 fragments certainly establishes a correlation with the Upper 

 Ordovician, and probably Maysville rather than Richmond. 



In the " Table of the Geologic Distribution of the North 

 American Species of Eurypterids at Present Known " (N. Y. 

 State Bull., Memoir 14, 1912, p. 431), representatives in the 

 Ordovician have been reported from the Normanskill shale, 

 the Schenectady beds, and the Utica. One species has been 

 reported from the Richmond. 



The bionomic interest of the find lies in the association of 

 the fragments with a typical marine fauna. One of the joints 

 was found resting against a specimen of one of the most 

 abundant of the Bays brachiopods. Such an association falls 

 in line with the general occurrence of Ordovician Eurypterid 

 remains with those of marine organisms. The delta-like and 

 near-shore character of the Bays sediments is evident. But 

 though the fragmental character of the Eurypterid remains indi- 

 cates transportation and a consequent breaking up of a complete 

 exoskeleton, the occurrence at Lyons Gap gives no indication 

 that this took place in a fresh water stream rather than in 

 surf along the shore. On the whole, the find seems to con- 

 firm Laurie's suggestion that Stylonurus possessed purely lit- 

 toral habits. 



Dept. Geology, Harvard University. 



