966 THE PALEONTOLOGY OF MINNESOTA. 



[Lophospira conolnnula. 



from the peripheral band they cross the space between the central and lower carinae 

 somewhat obliquely, thus indicating a deeper sinus in the outer lip. Casts of the 

 interior could not be distinguished excepting perhaps those which preserve the 

 aperture entire, when the difference last mentioned may serve. 



It is strange that two shells can be so very much alike and yet maintain certain 

 almost minute characters so persistently as in this case. We have 42 specimens of 

 the obliqua and there is never any doubt about them, the peculiarities mentioned 

 being very constant. 



Formation and locality. Rare in the upper partof theStones River group, at High Bridge, Kentucky; 

 more common in the Black River and Trentou groups at various points in Mercer county, Kentucky. 



Collection. E. O. Ulrich. 



LOPHOSPIRA CONCINNULA, n. sp. 



PLATE LXXII. FIGS. 16-19. 



Hight usually 10 to 15 mm., in one case reaching 21 mm.; apical angle 52 to 59. 

 Volutions six or seven, angular, not ventricose; upper central and lower carinae all 

 strong. Lines of growth fine, sharp, thread-like, regular, almost vertical beneath 

 the peripheral band, and but little curved backward above it. In the grooves 

 between the lines there are numerous short connecting bars, producing a minutely 

 cancellated appearance. 



The peripheral band and surface markings, excepting the delicate connecting 

 bars, are precisely as in L. bicincta, and we are satisfied that the new species is 

 closely related to that shell, if indeed it is really not merely a variety of it. Still, 

 the connecting bars are a feature deserving some recognition, and when we add that 

 the volutions in L. concinnula increases less rapidly and that they are less ventricose 

 and more angular, because of the greater prominence of the spiral carinae, it seems 

 to us that a specific distinction must be conceded. 



We describe three other species, L. pulchella, L. spironema and L. tenuistriata, 

 which, if the aperture is imperfect and the surface markings abraded, it would be 

 quite impossible to distinguish from each other and from L. concinnula. With any 

 part of the exterior layer of the shell preserved the difficulties vanish, the first 

 named three forms having a deep sinus in the outer lip and, therefore, strongly 

 recurved lines of growth, while in L. concinnula the retral curvature is, as in L. 

 bicincta, very slight indeed. The character of the transverse striae also is different, 

 being stronger and sharper in L. concinnula. For other differences see descriptions 

 of the species mentioned. 



Formation and locality.- Rlack River Kroup, Ctenodonta bed, Minneapolis and Cannon Fulls, 

 Minnesota. 



Collections. E. O. Ulrich (9 specimens); W. H. Scofleld (1 specimen). 



