Handbook of Paleontology 395 



hamiltonensis, Cypricardella bellistriata, Modiomorpha 

 niytiloides, Glyptodesma erectum; gastropods by Dia* 

 phorostoma lineatum, Loxonema hamiltoniae, Phanero- 

 tinus laxus, Platyceras bucculentum, Bellerophon leda, 

 B. rudis, Bembexia sulcomarginata, Euryzone rugulata, 

 E. lucina; cephalopods by Orthoc eras exile, Geisonoceras 

 subidatum, Spyroceras crotalum, Tornoceras uniangulare, 

 Parodiceras discoideum; trilobites by Proetus rowl, Pha- 

 cops rana, Homalonotus (Dipleura) dekayi, Dalmanites 

 (Cryphaeus) boothi. Other crustaceans found are Lep- 

 erditia punctulifera and Echinocaris punctata; and conu- 

 larids such as Hyolithes actis and Conularia undidata oc- 

 cur. The worm burrow Taonurus velum is quite charac- 

 teristic. 



In the eastern part of the State the Hamilton beds 

 above the Marcellus black shales have always been dis- 

 cussed as a unit, the Hamilton shales and flags. In 

 Ulster and Greene counties, the Hamilton has been di- 

 vided into two formations. The lower formation includes 

 the f ossiferous marine beds, 400 to 500 feet thick and 

 designated as the Mount Marion beds (Grabau '19) from 

 Mount Marion west of Saugerties ; the upper formation 

 contains nonmarine, nonfossiliferous, flagstone-bearing 

 beds, with a thickness of 500 to 600 feet, and has been 

 termed the Ashokan shales and flags (Grabau '19). The 

 Cornwall shale (Hartnagel '07; for Darton's "Monroe 

 shale") was named from exposures found at the town 

 of Cornwall, Orange county. These shales, 200 feet 

 thick, extend through the town of Monroe into New 

 Jersey and carry fossils indicative of Hamilton age. The 

 Bellvalc sliales (Darton '94) also occur in Orange 

 county and New Jersey, overlying the Cornwall shale. 

 These beds have a thickness of 1300 to 2000 feet, and 



