892 THE PALEONTOLOGY OF MINNESOTA. 



IBucanla micronenia. 



showing that the aperture is relatively larger in adult examples. The small 

 specimen, which is one of several, was at first believed to be distinct, but a careful 

 comparison of the whole series resulted in the conviction that the small examples 

 were merely immature. 



Formation and locality. Upper part of Trenton group, Mercer and Boyle counties, Kentucky. 

 Collection. E. O. Ulrich. 



BUCANIA MICRONEMA, tt. Sp. (Ulrich.) 

 PLATE LXVI, FIGS. 26-29. 



Of this form we have but a single example. Although closely resembling B. 

 sublata, B. lindsleyi and B. rugatina, in one or another feature, we are fully persuaded 

 of its specific distinctness. The specimen, which has the appearance of being 

 mature, is so much smaller than the second of the species mentioned that further 

 comparisons with it are probably unnecessary. As to B. sublata, the present shell 

 has it volutions narrowly rounded on the sides instead of sharply angular, its aper- 

 ture is relatively larger, and its surface markings, which are not visible to the 

 unassisted eye, are much finer. Compared with B. rugatina, with which it was 

 found, its volutions expand more rapidly, giving a wider aperture, and its surface 

 markings are much finer. Besides the transverse lines are much less distinct and 

 not wave-like, while the lines running in the opposite direction, of which there are 

 about five instead of two in 1 mm., are not only finer but more continuous, appearing 

 like irregular wavy, knotted lines, running obliquely forward from the umbilicus to 

 the slit-band. 



Formation and locality. Near top of Trenton group, Danville, Kentucky. 

 Colkction. E. O. Ulrich. 



BUCANIA SIMULATEIX, n. sp. (Ulrich.) 



PLATE LXIII, FIGS. 48 and 49; PLATE LXVII, FIG. 45. 



Shell large, known from casts of the interior only. These consist of three or 

 four comparatively slender and loosely coiled volutions, leaving a large umbilicus 

 in which all the inner whorls are clearly exposed. Volutions somewhat reniform 

 in section, narrowly rounded in the ventral third of the sides, the ventral surface 

 gently concave, the dorsal part of the section nearly semi-circular. Last volution 

 obtusely carinated, with the dorso-ventral diameter increasing toward the aperture 

 more rapidly than is the case with the inner volutions, the hight and width of the 

 whorl just behind the aperture being about equal, while at the smaller end the two 

 dimensions are respectively about as three is to five. Aperture somewhat triangu- 

 lar-ovate, wide below, the expansion taking place chiefly at the lower part of the 



