236 bulletin: museum of comparative zoology. 



Professor Powell was good enough to spend three days in showing 

 the writer this section, and my interpretation of it differs somewhat 

 from that in his published account. The cherty magnesian limestone 

 at the base (zone 1) appears to belong to the Beekmantown, not tEe 

 Chazy, and Ophiletas were found in the upper beds. Zone 2 is a fine- 

 grained buff limestone with numerous gastropods and some trilobites. 

 At the base is a conglomerate with pebbles of magnesian limestone 

 and chert in a calcareous matrix. This formation is to be correlated 

 with the Mosheim of southw^estern Virginia and eastern Tennessee, 

 and that in turn is correlated with the lower part of the Stones River 

 of central Tennessee. 



The coarse-grained dark limestone of zone 3 is very fossil if erous, 

 some of the genera present being Hormoceras, Amphilichas, lUaenus, 

 Isotelus, Orthis, Dinorthis, Plaesiomys, Oxoplecia, Leptaena, Plectam- 

 bonites, and Solenopora, besides numerous bryozoans. This fauna 

 is much more like that of the Black River of Xew York than it is like 

 any fauna of the Chazy in the typical region, Oxoplecia and Plectam- 

 bonites in particular being unknown in the Chazy. On the other 

 hand, the fauna is more or less like that of the Holston and Lenoir of 

 eastern Tennessee, and these latter formations seem to be of Middle 

 Chazy age. The relation of this formation to the one below is exactly 

 like the relation of the Leray to the Lowville in Xew York. The line 

 of separation between the dark, impure limestone above and the pure 

 light-colored limestone below is a sharp one, and yet the top of the one 

 formation and the bottom of the other are combined to form a single 

 layer; a so-called "welded contact." 



The Athens shale (zones 4 and 5) is a dark fossiliferous shale in the 

 lower portion, and passes rather gradually into an almost entirely 

 unfossiliferous blue limestone above. Ncmagraptus gracilis and Didy- 

 mograptus occur in the lower part of the shale, while Dicellograptus, 

 Climacograptus, and the beautiful synrhabdosomes of Diplograptus 

 are most abundant at about the middle. Am pyx americanus appears 

 to begin its range with these latter fossils, being heae accompanied by a 

 Triarthrus, and extends up into the limestone of zone 5. In the upper 

 part of its range, I found it accompanied by Cryptolithus, Robergia, 

 and Acrothele. The Athens is plainly equivalent to the Xormanskill 

 of Xew York, and the Lower Dicellograptus shales of Sweden. 



Zone 6, the Tellico sandstone, is practically unfossiliferous here as 

 elsewhere. Upon it rests a thick mass of shale with some thin-bedded 

 limestone. This formation is generally called the Sevier in south- 

 western Virginia, and has not yet been studied in sufficient detail to 



