290 New York State Museum 



western New York, although the Frankfort was not rec- 

 ognized as a distinct member. The Frankfort shale 

 (Vanuxem '40) was named from the typical exposure 

 along Moyer creek southwest of Frankfort, Herkimer 

 county, where it is overlain by the Oneida conglomerate 

 (Silurian). It extends from the Mohawk north and west 

 into Lewis and Jefferson counties. In eastern New York 

 the Indian Ladder beds of the same age occur. The 

 Frankfort beds attain their greatest development in the 

 Utica basin where they have a thickness of about 500 

 feet. They thin out northwestward and westward pass 

 under younger formations. These beds consist of black 

 and gray argillaceous shales, prevailingly more gray than 

 the Utica. Its fauna, as found in the shales at Frankfort, 

 connects the formation with the Utica instead of the 

 typical Lorraine (Pulaski) beds. The fauna includes 

 Utica graptolites as Climacograptus pygmaeus, C. typi- 

 calis, Glossograptus quadrimucronatus ; brachiopods as 

 Leptobolus insignis, Schizomania filosa; the worm Serpu- 

 lites crassimarginalis ; the cephalopod Geisonoceras tenu- 

 istriatum mut. frankfortense; and the trilobite Triarthrus 

 eatoni. The appendages of the famous Triarthrus eatoni 

 described as becki by Beecher came from these beds. 

 Other Frankfort forms not occurring in the Utica are 

 the graptolites Mastigograptus laevis and Inocaulis arbo- 

 rescens, the brachiopod Lingula progne and the trilobites 

 Cryptolithus bellulus and Proetus beecheri. The fossils 

 characteristic of the Frankfort shales, are the brachio- 

 pods Camarotoechia? humilis and Leptobolus insignis 

 latus, the cephalopod Geisonoceras tenuistriatum frank- 

 fortense and the trilobites Cryptolithus bellulus and Iso- 

 telus stegops. 



The Pulaski shales (Vanuxem '40) received their name 

 from the village of Pulaski in Oswego county, where the 



