904 THE PALEONTOLOGY OF MINNESOTA. 



[Couradella. 



Collectors have heretofore identified this species with Hall's Bucania expansa 

 from the Trenton of New York,* but a comparison proves it quite distinct. In the 

 first place, though of about the same size, there is one volution less. Next, the last 

 volution is relatively narrower and higher just behind the aperture, and the latter 

 very differently outlined. Finally, the last volution is nowhere triangular as is 

 the case in the Trenton species. Compared with S. buelli and S. sculptilis the 

 outer volution will be found much larger especially as regards the dorso-ventral 

 diameter. 



In practice the most difficult perhaps to separate from this species is the 

 associated Bucania simulatrix. Though of widely different affinities, casts of these 

 two species, especially when, as is usually the case, the aperture is imperfect, are 

 very apt to be confused. Still, after familiarizing one's self with certain differ- 

 ences, they may be distinguished almost at a glance. In the first place the volutions 

 of the Bucania are more slender. This difference is particularly striking in an 

 apertural view, the small end of the outer volution, in specimens of the same hight, 

 being at least a fourth wider in the Salpingostoma. In the Bucania again the width 

 of the last volution continues to increase quite uniformly instead of being almost 

 constricted near the aperture. When the latter is preserved the difficulties have 

 vanished, for this part is readily distinguishable. 



Formation and locality. Richmond group of the Cincinnati period, at Richmond, Indiana, where 

 casts of it occur rather abundantly. Good specimens, however, are anything but common. 



Collection. E. O. Ulrich. 



Genus CONRADELLA, n. gen. 



Phragmoiites, CONUAD, 1838, Ann. Geol. Rep. New York, p. 119. 



Cyrtolites (part.), HALL, 1847 and 1871. MEEK and WORTHKN, 1868. MEEK, 1873. S. A. MILLER, 

 1874 and 1892. 



For generic characters and list of species see pages 851, 852. 



It is strange that this sharply defined genus of shells has been so uniformly 

 confused with Cyrtolites. Aside from the fact that the whorls are similarly coiled 

 in the two groups, there is not a single character in which they are identical. While 

 the typical forms of Cyrtolites have no slit-band and in some cases not even a sinus 

 in the outer lip, Conradella has not only a sharply defined raised band, but an 

 unusually long apertural slit as well. The form of the volutions also is different, 

 the transverse section in the former being more or less rhomboidal, while in the 

 latter it is ovate or obcordate. Finally, the surface markings are not at all similar, 



The erroneous identification of this and :i number of other Trenton fossils In the upper member of Hie <!iiieinn:itl 

 period, Is responsible fur ih, .,,,,,,, , n i y pre.valllni; yet groundless Idea that the faun lofllie "Olnclinuiti croup" Is a sort of 

 mixture of "Trenton and Hudson River types." The sooner paleontologists will come to realize that a careful comparison 

 ..f tin fossils tin -in si -i vi 's i, one of the first necessities in a successful identification or discrimination, the better it will be 

 for stratlgraphlcal geoloRy. Mistakes are always possible, but time and care will avert most of them. 



