62() THE PALEONTOLOGY OF MINNESOTA. 



|S;iiVordla ventrults. 



Named as a small compliment to the veteran geologist, Prof. J. M. Saftord, State 

 Geologist of Tennessee. Science is indebted to him for several most valuable woi'ks 

 on the geology of his state, while personally I am under great obligations to him 

 for assistance in the way of specimens and advice. 



SAFFORDIA VENTRALIS, n. sp. 



PLATE XLI, FIGS. 3t 41. 



Shell transversely subovate, the hight and length very nearly as four is to five; 

 beaks small, declining, situated at the anterior extremity of the distinctly arcuate 

 dorsum, and projecting forward as far as the margin of the shell beneath it. Anterior 

 margin distinctly concave in the middle, the lower part narrowly rounded; ventral 

 margin rather strongly convex, posterior margin subtruncate, a little oblique, the 

 upper half straight or slightly sinuate, the lower rounded. Surface of valves mod- 

 erately convex, with a very inconspicuous umbonal ridge between which and the 

 dorsal edge there is a shallow sulcus. Escutcheon well defined, extending the full 

 length of the hinge, in a dorsal view very narrow between the beaks, wide at the 

 middle, and nan-owing again posteriorly. Lunule sharply defined, very deep, nearly 

 twice as long as wide. Surface marked by subimbricating concentric growth lines. 

 These are rather small but sharp and of nearly equal size for a short distance 

 beneath the cardinal edge, and only a few of them seem to cross the umbonal ridge. 

 Internal characters of hinge as shown in figures 37 and 41. Anterior muscular scar 

 of medium size, subcircular, deep, showing very prominently on casts of the interior; 

 pallial line and posterior muscular impression very faint. 



This species is distinguished from S. sulcodorsata by its shorter form, terminal 

 beaks, and more rounded ventral margin. 



Formation and locality. Upper beds of the Hudson River group ne;ir Spring Valley, Minnesota, ami 

 Iron Ridge, Wisconsin. 



SAFFORDIA SULCODORSATA Vlrich. 



I'LATF. XI, I. KKiS. Vi and :tl. 



Cuneamya sulcodorsata ULiucn, 1892. Nineteenth Ann. Rep.Geol. and Nat. Hist. Sur. Minn., p. 248. 



Shell small, moderately convex, oblong-subquadrate, with the dorsal and ventral 

 margins subparallel and gently convex, the posterior end truncate, very slightly 

 produced and sharply rounded at the base, anterior end very short (long for the 

 genus), narrowly rounded. Beaks subterminal, declining forward, strongly incurved, 

 projecting forward rather than upward; umbonal ridge moderately prominent, not 

 angular. Dorsal slope with a distinct expanding sulcus; ventral and anterior slopes 

 gently and uniformly convex. Hinge line, posterior to the beaks, long, the edge 



