ENDOCERATID^. 
135 
Wahlenberg’s description, which is almost certainly confirmed by 
his reference to one of Klein’s figures (‘ Descriptiones Tubulorum 
Marinorum,’ 1731, tab. vi. figs. 1, 2), it was most probably Endo- 
ceras trochleare. 
It appears that Wablenberg’s views regarding the imprisoned 
specimen were not shared in by some of bis scientific brethren, 
for be observes with much nciivete that “ many people interested 
in natural phenomena have regarded this internal Orthoceratites 
as a different species, on account of its annular form ; ” and the 
inhabitants of Mount Kinnekulle well distinguish it from the 
common Orthoceratites under the name “ Svecico skrufstenar ” 
[Swedish screw-stone], a by no means inapt sobriquet for Endoceras 
trochleare. 
Ebminating from Wahlenberg’s description of “ Orthoceras 
duplex ” those parts of it which are essential to a specific diagnosis, 
they are found to consist of two only, viz., the form of the shell, 
which is said to be “ rather cylindrical than conical,” and the pro- 
portionate size of the siphuncle, “ occupying about a third part of 
the entire shell.” These two characters would obviously not be 
sufficient for specific distinction ; and the vagueness of the original 
description has given rise to a number of widely differing forms 
being placed under one specific name, according to the interpretation, 
generally a very liberal one, that each author has put upon the 
description. To make confusion worse confounded, another of 
that author’s species — “ Orthoceras commune ” — has become en- 
tangled in the nomenclature of “ 0. duplex.” According to the 
original description of the former (Kov. Act. loc. cit. p. 85) 
0. commune is not an Endoceras, but an Orthoceras, for the 
siphuncle is described as of moderate thickness, “ equal to nearly 
a tenth part of the diameter of the whole shell, taken transversely,” 
and “ is for the most part situated midway between the axis and 
the circumference of the shell.” Hisinger who was the first to 
give figures of fossils under Wahlenberg's names du'plex” and 
commune,’^ adds very little to our knowledge of those forms, 
and to his brief deseription of the former he appends the words 
an speeies distincta?” — a somewhat significant phrase, which seems 
to suggest the difficulty he experienced in identifying Wahlen- 
berg’s species. 
Having thus failed in obtaining the required information from 
books, I explained my difficulties to Dr. Lindstrom, and he, with 
no less kindness than promptitude, caused enquiries to be made for 
^ Letbsea Sveeica, 1837, p. 28. 
