924 THE PALEONTOLOGY OF MINNESOTA, 
[Bucanopsis. 
resembles Protowarthia granistriata more closely in this respect than either Bucanella 
trilobata Conrad sp., or Kokenia esthona. 
The longitudinal striation, unusual width and elevation of the slit-band, the 
last feature producing an obscure tripartite character to the shell, seem to be the 
principal characters upon which Koken bases his conception of Bucanella as distinct 
from Bucania, which with him included Bucanopsis. These features he finds in his 
B, esthona, Krause’s B. substriatus and in several other Silurian and Devonian shells 
which he assumes to be related to species upon which Meek founded Bucanella. 
This assumption, however, is totally unwarranted, and in the absence of sufficient 
evidence to prove his point Koken should not have charged Meek with an incorrect 
description. 
The elevation of the slit-band in the group of species under consideration is 
probably not of much consequence, though usually present. Its unusual width, 
however, may be of importance but we see no way of utilizing it at present. The 
extension of the revolving lines over the slit-band also seems to us to be of little 
value. We came to this conclusion because they may be present in one and absent 
in the other of two closely related species. For instance, in Bucanopsis textilis Hall 
(not De Koninck sp.), of the Warsaw or St. Louis group, the slit-band seems always to 
be without revolving lines, but in an undescribed form recurring in the Chester 
group of Kentucky, and which can scarcely be distinguished, such lines are clearly 
present. We find them also in B. leda Hall, while they are absent in the closely 
related B. lyra Hall. Then they are developed again in some of the Carboniferous 
species, notably B. marcouiana Geinitz, B. ellipticus McChesney, and B. montfortianus 
Norwood and Pratten, the last belonging to the Bellerophon patulus group of species. 
It seems to us, therefore, unreasonable to accord any more than specific importance 
to the presence or absence of these lines. 
There is another assertion made by Koken to which we must take exception. 
He says that B. esthona is “obviously a combination of the characters of the so-called 
Euphemus and Bucania.’ This observation is so totally at variance with our own 
opinion that we are almost at a loss to answer it except with a simple contradiction. 
He is most assuredly far from the truth if he means to imply that the revolving 
ridges of Huphemus, which we cannot for a moment doubt are really folds of an 
extension of the inner lip, are in any way comparable with the spirally ribbed 
external surface sculpture of Bucania and Bucanopsis. 
