126 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



LINGULA ^VINONA ( n. s.). 



PLATE VI. FIG. 9. 



Shell small, subquadrilateral, the front nearly straight ; sides 

 nearly straight and parallel : apex obtuse, the cardinal margins 

 sloping at an angle of eighty degrees. Surface marked by tine 

 concentric striae. 



This species occurs among some obscure and imperfect specimens from 

 Lansing in Iowa, and is readily distinguished by its short broad form, being 

 less than a fourth of an inch in length and breadth. It is quite distinct 

 from any of those in the lower or upper beds of the series ; occurring more 

 than two hundred feet below the Lower Magnesian limestone, and near the 

 middle of the Potsdam sandstone. 



LINGULA MOSIA (n.s.). 



PLATE VI. FIGS. 1 - 3. 



Shell small, subelliptical or ovate-spatulate, little convex, con- 

 centrically striated. The slopes below the beak are sometimes 

 nearly straiglit for a short distance, and often curving from the 

 beak to the base. The specimens are for the most part impres- 

 sions in sandstone, with little of the shell remaining, but the 

 form is very distinct from any of the described species ; and 

 being limited in vertical range, and with a somewhat wide 

 horizontal extension, it becomes of interest in its associations. 



I have given three varieties of form, which for the present I refer to a 

 single species. 



Fig. 1. An elliptical form which presents some characters indicating a distinct species, 

 but which for the present I leave with the others. 



Fig. 2. A specimen of the ordinary size, with nearly straight sides and front, and the 

 cardinal slopes straight. 



Fig. 3. An ovate form, from the same horizon. 



Fig. 3 a. a more broadly ovate form from the Calciferous sandstone at Stillwater, 

 Minnesota. 



This species is intermediate, in form, between L. antiqua and L. prima 

 of the Potsdam sandstone in New- York, but is distinctly different from 

 either of them. It occurs in the same association with Dikelocephahis min- 

 nesotensis at Lagrange mountain in Minnesota, and in the same horizon 

 and similar association near Mazomania, Wisconsin. 



LINGULA AUROKA. 



PLATE VI. FIGS. 4 & 5. 

 Lingula aurora : IIall, Annual Geological Report of Wisconsin, 1860-61. 



Shell broadly ovate : beak obtuse, appressed, a little more at- 

 tenuate in the ventral valve ; sides abruptly diverging from the 

 beak including between them an angle of about 85°. Cardinal 



