896 THE PALEONTOLOGY OF MINNESOTA. 
[Bucania peracuta. 
a very thin callosity over the back of the preceding whorl. Surface sculpture 
consisting of sharp, regular, rather closely arranged and but very little curved striz 
of growth, and exceedingly fine, obliquely revolving lines, the latter obscure on even 
the best specimens. Slit-band raised, distinct, narrow, concave, bordered on each 
side by a sharply elevated thin line; lunule not very distinct. Out of eleven speci- 
mens the largest is about 10 mm. high, the smallest about 5mm. In an average 
shell the hight is 7.0 mm.; the diameter at right angles to the hight 5.2 mm.; the 
width of the aperture 5.5 mm.; its hight about 5.0 mm.; greatest width of umbilicus 
about 2.0 mm. 
Variety suppaTuLa, ». var. (Ulrich.) 
PLATE LXVI, FIGS. 45 and 46, 
Under this subordinate name we propose to classify provisionally three speci- 
mens found in association with B. nana, but differing in several respects from the 
typical form of the species. Thus, the aperture is wider, its width fully equalling 
the greatest diameter of the shell. Then the umbilicus is narrower, being almost 
closed. On one of the specimens the surface is in good condition, but we failed to 
notice any evidence of the delicate revolving lines occurring on no better preserved 
examples of B. nana. If it could be shown that these lines are always absent, then 
we would favor a removal of the supposed variety to the genus Bellerophon, in which 
case the varietal name should be promoted to the specified rank. We may add that 
we have before us three casts of the interior from the lowest beds at Cincinnati, 
Ohio, that look very much as if they might belong to this variety. 
We are not satisfied that either the variety or the species is a true Bucania. 
The umbilicus is too small and the sculpture not what it should be. The markings 
of B. nana are considerably like those found on Tetranota bidorsata, but the nana 
is most certainly not a Tetranota. We suspect that the species and variety are close 
relatives of two Clinton group shells described by Foerste as Bellerophon or Bucania 
exigua and fiscello-striata. In the surface markings, the last reminds one also of 
Bucania punctifrons. All five of these forms require further study before their 
positions can be established. 
Formation and locality.x—Upper part of Trenton group, Mercer county, and Covington, Kentucky. 
Collection.—E. O. Ulrich. 
Bucania pERAcuTA, n. sp. (Ulrich.) 
PLATE LXVI, FIGS, 34 and 35. 
Of this remarkable shell we have seen only a single imperfect specimen which 
was collected by Prof. J. M. Safford and kindly sent to one of the authors for 
