250 BULLETIN: MUSEUM OF COMPARATIVE 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- 
graptus eucharis, Glossograptus quadrimucronatus var., Climacograptus 
putillus, ete., and in the shale above the Trenton of Trenton Falls, 
Leptograptus annectans 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 evidence. 
Some of the more important fossils of the formation are :— 
Azygograptus sp. C. typicalis Hall. 
Mastigograptus cf. M. simplex Wal- Lasiograptus eucharis Hall. 
cott. Rafinesquina ulrichi James. 
Diplograptus vespertinus Ruedemann. T'rocholites ammonius Conrad. 
Climacograptus bicornis ulttmus Ruede- Triarthrus becki Green. 
mann. Cryptolithus 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 Utica of the Holland Patent type, but both Climaco- 
graptus typicalis and Lasiograptus eucharis are very abundant in the 
typical Utica. 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 anywhere 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 
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