214 The American Geologist. ^i^''^' ^9*^3- 
In this connection, it is still further to be considered 
that endoceratites of the Trenton attained a length of six- 
teen feet or more. While it is already difficult to under- 
stand how these giants could have balanced themselves upon 
their apex, it would appear still more unintelligible that they 
should have striven to raise themselves so high above the sea 
bottom when their recent descendants find it so much more 
advantageous to lie low in the mud and to prey upon the much 
richer fauna of the vagile benthos. Besides, in the Trenton 
period, the fish-fauna was certamly small and the majority of 
all organisms, which we have from that period, were still bot- 
tom-crawlers. These considerations suggest to me the sup- 
position, that the orthoconic cephalopods may have fixed 
themiselves only in their youth to small objects, tO' gain a foot- 
hold, as professor v. Martens suggested, but later on may 
have allowed themselves to sink, or actively worked themselves 
into the ooze and perhaps also may have piled sediments 
around them, in order to gain steadiness and to hide them- 
selves. ■ The occurrence of numerous upright orthoceratites in 
the Oneonta beds of New York also mentioned in the discus- 
sion of the theses, may serve to support this view, in case it 
can be proved that the orthoceratites were killed in situ by an 
inflow of fresh water, as is indicated by the presence of Am- 
nigenias. 
The objection that no other orthoceratites, with the excep- 
tion of those just mentioned, are found in vertical position in 
the sediments, is probably to be met by the observation that 
the shells of the recent Nautilus, which is a bottom-crawler, 
and even those of the Spirula which lives sessile at considerable 
depth, rise after the death of the animals to the surface and 
become pseudo-planktonic, a fact fully established by Walther 
(Zeitschrift der Deutsch. Geol. Gesellsch., 1897, 49:258). The 
cause of this phenomenon, if the chamber during- life time of 
the animal were filled with water, is not quite apparent, but 
perhaps is to be sought in the decay of the organic tissues ; 
and it is to be inferred that the same took place with the ex- 
tinct cephalopods and to^ some extent also with the shells of 
Orthoceras. The writer has seen exposed near Valcour, Lake 
Champlain, on large surfaces of Beekmantown limestone, which 
were clearly shore-deposits of that period, the tangled growth 
