250 BULLETIN : MUSEL'^H OF COMPARATR^E ZOOLOGY. 



shale equivalent of the Lower Trenton, Corynoides calicularis and 

 Diplograptus amplexicaulis, in the shale equivalent of the remainder 

 , of the Trenton (as exhibited in the Trenton Falls section) Lasio- 

 graphis evcharis, Glossograptus quadrimucronatus var., Climacograptns 

 pntiUus, etc., and in the shale above the Trenton of Trenton Falls, 

 Leptograptus annedans and the other fossils listed above. 



If we now return to the Lower Mohawk Valley, we find above the 

 Canajoharie shale the Schenectady formation, composed largely of 

 sandy shale and sandstone, but containing some graptolites and other 

 fossils. Our knowledge of this fauna is due almost entirely to Dr. 

 Ruedemann. That author has correlated the Schenectady with the 

 Upper Trenton, but, to my mind, on very inadequate e\ddence. 

 Some of the more important fossils of the formation are : — 



Azygograptus sp. C. typicalis Hall. 



Mastigograptus cf. M. simplex Wal- Lasiograptus eucharis Hall. 



cott. Rafincsquina ulrichi James. 



Diplograptus vespertinvs Ruedemann. .Trocholites ammonius Conrad. 



Climacograptus bicornis ultimus Ruede- Triarthrus becki Green. 



mann. CryptoUthns tessellatus Green, 

 and numerous eurypterids. 



Ruedemann states that this fauna bears a Utica aspect, but that 

 the graptolites point as much toward the Canajoharie fauna as toward 

 the typical Utica. In this connection we must note the absence of 

 Diplograptus amplexicaulis, Corynoides calicularis, and Glossograptus 

 quadrimucronatus. It is true that none of the graptolites listed are 

 confined to the L^tica of the Holland Patent t\-pe, but both Climaco- 

 graptus typicalis and Lasiograptiis eucharis are very abundant in the 

 typical L'tica. The presence of a Mastigograptus comparable to M. 

 simplex also suggests Utica, as does the presence of Eurypterida. 

 Finally, and most important, is the presence of Cryptolithus tessellatus, 

 a fossil which to Dr. Ruedemann suggested the Trenton age. 



The geological range of Cryptolithus tessellatus seems to be quite 

 generally misapprehended. It is frequently thought of as a fossil 

 which occurs almost am-where in the Trenton, whereas, as a matter 

 of fact, it is restricted to certain definite horizons and is not every- 

 where present. 



The earliest appearance of Cryptolithus in New York is very near 

 the base of the Trenton, where it is exceedingly abundant in the 

 Glens Falls formation. At this horizon it is very abundant near 

 Quebec, at Montreal, in the Champlain Valley, and the Mohawk 



