896 THE PALEONTOLOGY OF MINNESOTA. 



[Bucania peraouta. 



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 striee 







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; lunulae not very distinct. Out of eleven speci- 

 mens the largest is about 10 mm. high, the smallest about 5 mm. In an average 

 shell the bight is 7.0 mm.; the diameter at right angles to the bight 5.2 mm.; the 

 width of the aperture 5.5 mm.; its bight about 5.0 mm.; greatest width of umbilicus 

 about 2.0 mm. 



Variety SOBPATULA, n. 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. Upper part of Trenton group, Mercer county, and Covington, Kentucky. 

 Collection. E. O. Ulrich. 



BUCANIA PEKACUTA, n. sp. (Ulrich.) 



I'I,ATK I. XV I. FHiS. M itml ,',:,. 



Of this remarkable shell we have seen only a single imperfect specimen which 

 was collected by Prof. J. M. Saflord and kindly sent to one of the authors for 



