Jaekel on Orthoccras. — Ruedcmann. 211 
will aid in rendering our conception of these forms more con- 
cise by bringing out observations stored up in the notes of in- 
vestigators. With this purpose this translation has been pre- 
pared and the present writer desires to add a few annotations 
to these significant contentions. 
It has been asserted on various excellent grounds that life 
originated in the coastal regions with benthonic forms ; that 
slowly creeping organisms preceded the planktonic and 
nektonic forms in the lower phyla oi the animal kingdom. 
This principle may, in its totality, be well applied to the 
Cephalopoda, for here all the living forms are mostly 
rapid movers in contrast to the evidently sluggish forms 
with heavy shells, belonging to the earl}^ geologic per- 
iods. In the Mesozoic we find the ammonoids, which for good 
reason, are now considered as bottom crawlers ; and as we go 
back in time in the paleozoic we find the coiled forms largely 
replaced by the orthoceracones. Notwithstanding the fact that 
Barrande demonstrated that the whole series of forms from 
the straight to the involute nautiloids was present in the earliest 
period, and the declaration of Jaekel (in explanation of thesis 
6) that the slightly curved forms are not transitional between 
the involute nautiloids and the orthoceracones, but are tyj^es 
of repression of development of the former, and that, further, 
the majority of these faintly involute forms do not appear luitil 
Upper Siluric and Devonic time, it can be statistically estab- 
lished, as Hyatt affirms, "that the straight cones predominate 
in the Silurian and earlier periods ; while the loosely coiled are 
much less numerous, and the close coiled and involute, though 
present, are also^ rare." We cite here Hyatt's lucid exposition 
of these facts (Phvlogenv of an Acquired Characteristic, p. 
366) : 
"But suppose we reverse the course of nature and follow 
back the diminishing number of nautilian and gyroceran shells. 
We then see, upon arriving at the Silurian, that the vanishing 
point of these shells, although not traceable on account of the 
lost records of Protozoic time, could not have been far distant, 
while the increasing number and varied forms of the strai2:ht 
cones indicates for them a more remote focus in time and con- 
sequently a more ancient origin. Thus we arc able to see that, 
antecedent to the Silurian, in the Protozoic, there nuist have 
