Editorial Comment. L15 
shown that the protoconch in a single specimen referred to 
Bactrites, is ovoid,* but in the examples from the Naples beds 
it is much. shorter, subspherieal and its resemblance to that of 
this Orthoceras very close. As far as I am aware the course 
of lateral (dorsal) sipho across the first chamber of the shell 
has not before been ascertained in Bactrites, but it is here 
clearly evident that the siphonal passage on the first septum 
is distinctly lateral and does not change to a central position 
in traversing the first chamber. 
With this point determined there seems no reason to ques- 
sion that this protoconch is one of the Orthoceras which has 
undergone no atrophy or resorption. Perhaps some explana- 
tion of its fullness and comparatively great size may be found 
in the following consideration. The associated individuals of 
Bactrites bearing protoconchs are, to a very large degree, 
actual young shells retaining the chamber of habitation, and 
not fragments of partially grown or mature individuals. Sim- 
ilar young and nearly entire shells of Orthoceras have also 
been found, but without the protoconch. It is probable that 
this protoconch has been derived from a shell so young that 
atrophy and wrinkling have not manifested themselves as they 
may have done with the more mature development of the 
shell. This, I believe, is the only recorded observation of the 
protoconch in palaeozoic forms of Orthoceras and its shrunken 
condition in the post-pala±ozoic forms may have a phyletic 
significance. Attention may be directed to the remarkable 
similarity in form between this protoconch and that of Belem- 
nites, as given b} r Branco.f The difference in the two lies 
wholly in the position of the sipho which is lateral at the first 
septum of Belemnites and hence the protoconch of the latter 
is a notable reproduction of that of Had rites. 
EDITORIAL COMMENT. 
In the August number of the "Popular Science Monthly" 
Major Powell, the director of the U. S. Geological Survey, has 
published an article apparently in reply to one that appeared 
*Zeitschrift der deutsch. geolog. Gesellschaft, vol. 37, p. 3, 1885. 
tQp. cit. vol. 32, p. 608, 1880. 
