510 bulletin: museutm of comparative zoology. 



Dalmanella macrior (Sardeson), 



Orthis macrior Sardeson, Bull. Minn. acad. sci., 1892, 3, p. 330, pi. 5, fig. 5-7. 

 Orthis {Dalmanella) testudinaria var. emacerata Winchell and Schuchert, 



Geol. Minn., 1893, 3, pt. 1, p. 445, pi. 33, fig. 23-24. 

 Orthis emacerata Sardeson, Amer. geol., 1897, 19, p. 102, pi. 5, fig. 14-18, 28. 



Shells subquadrangiilar, broadest at or near the hinge; nearly as 

 long as wide. 



Pedicle-valve convex; brachial nearly flat; concentric lines some- 

 times present. A single median plication is prominent near the pedi- 

 cle-beak. The median fold grows wider and higher toward the 

 anterior margin and is bounded by depressed areas. 



The brachial-valve has a corresponding depression, and the stria- 

 tions resemble those of D. rogaia Sardeson. There is a total lack of all 

 minuter surface markings. 



Typical specimens measured: — 



The common Dalmanella found in the Maquoketa at Clermont has 

 usually been called D. emacerata, but differs from it in having a deeper 

 sinus and more pronounced fold, and in having the lateral margins 

 more nearly parallel. Sardeson's name for the species may therefore 

 be revived although he himself did not use it in his second paper. 



Locality: — Maquoketa in Minnesota; Lower Maquoketa at Cler- 

 montj Iowa. 



Dalmanella corpulenta (Sardeson). 



Orthis corpulenta Sardeson, Bull. Minn. acad. nat. sci., 1892, 3, p. 330, pi. 5, 

 fig. 8-10. Amer. geol., 1897, 19, p. 107, pi. 4, fig. 11-19. 



Orthis {Dalmanella) testudinaria var. meeki Winchell and Schuchert (non 

 Miller), Geol. Minn., 1893, 3, pt. 1, p. 445, pi. 23, fig. 25-29. 



A few specimens appear to belong to this species, which is common 

 in the Maquoketa of Minnesota but unknown elsewhere. The hinge 

 is short, the form subcircular in neanic but rather elongate in adult 

 specimens, the median fold is not strongly delineated, and the sinus 



