RAYMOND: CORRELATION' OF THE ORDOVICIAX STRATA. 247 



In zone 2 the only graptolites are Amplexograptus vasae and Cory- 

 710 ides curius. 



Zone 1 contains Climacograptus scharenbergi and C. rugosus. 



In America the zone of Dicranogmptus clingani, though that species 

 itself is not present, is found in the shales of eastern New York and 

 Canada. These shales were long called Utica, but Ruedemann 

 (113 and 117) has shown that they are older and equivalent to the 

 calcareous Trenton of Central New York. The shales are also 

 involved in the mass of the so-called Hudson River shales in the Hudson 

 . Valley. They are the Cumberland Head shales of the Champlain 

 Vallev, the Snake Hill shales of the Hudson Vallev, and the Cana- 

 joharie shales of the Mohawk Valley. 



At Canajoharie. the type-locality for the formation of that name, 

 Ruedemann {117) found the following sequence of faunas: — 



At the base, are seventeen feet of dark blue fossiliferous limestone 

 with interstratified shale beds. This limestone is basal Trenton and 

 contains the Cryptolithus fauna in the limestone, while the interstrati- 

 fied shale afforded Corynoides calindaris, Diplograptus amplexicaulis, 

 and Mesograptus mohawkensis, so that we here have an indication of 

 the fauna of the shaly equivalent of the Glens Falls limestone. 



Above this comes the Canajoharie shale, which is strongly cal- 

 careous in its lower portion, becoming truly argillaceous above. 



In the lower sixty-five feet of the Canajoharie, Diplograptus amplexi- 

 caulis is the only graptolite, while in a zone between 65 and 120 feet 

 above the base of the formation, Corynoides calicidaris, Diplograptus 

 putiUns, and Lasiograptus eucharis are added. Brachiopods, pelecy- 

 pods, and crustaceans are fairly common in both zones. In the zone 

 from 115 to 150 feet above the base Glossograptus quadrimucronatus 

 cornutu^ appears, associated with some of the previously mentioned 

 graptolites. These pass up through the next 120 feet, to 270 feet 

 above the base of the formation. Triarthrm becki is not noted until 

 a height of 190 feet above the base of the formation, when it appears 

 suddenly in great numbers. 



Thus, combining the information obtained from the Canajoharie 

 and Sprakers sections — these localities are only about two and one 

 half miles apart — Ruedemann made out four faunal zones. 



4. Zone of Climacograptus spiniferus, Diplograptus vespertintLS, 

 and Lasiograptus eucharis. 



3. Zone of Lasiograptus eucharis, Trocholites ammonius, etc. 



2. Zone of Glossograptus quadrimticronatus comutus, Corynoides 

 calicularis, etc. 



