Oyrtodonta grandis.] 



LAMELLIBKAN0H1A.TA. 



547 



Casts of what may be a small variety of C. tenella occur in the Trenton limestone 

 at Minneapolis. The largest seen (Mus. Reg. No. 700), is only 12 mm. long. Aside 

 from the matter of size, they agree very well indeed with the types of the species. 



Formation and locality.— Vpnev part of middle third of the Trenton shales, about six miles south of 

 Cannon Falls, Minnesota. 



Mus. Reg. No. 8336. 



Cyrtodonta grandis Ulrich; and varieties. 



PLATE XL, FIGS. 9-14. 



Cypricardites grandis Ulrich, 1890. Amer. Geol., vol. vi, p. 387. 



Cypricardites germanus ULRicn, 1892. Nineteenth Ann. Rep. Geol. and Nat. Hist. Sur. Minn., p. 236. 



Cypricardites lueulentus Sardeson, 1892. Bull. Minn. Acad. Nat. ScL, vol. iii, p. 338. 



Fig. 43. Cyrtodonta grandis, and varieties, a and b, anterior and lateral views of a perfect speci- 

 men, upper Trenton, two miles south of Burgin, Kentucky, c and cZ, lateral and antero-cardinal views 

 of a small left valve of same, with stronger surface markings than usual; from same formation and 

 locality, e, nearly entire cast of the interior of a left valve, from same locality. /, small fragment of 

 a cast of the interior of a left valve, preserving sharp impressions of the anterior adductor scar and 

 cardinal teeth, g, the cardinal part of a cast of the interior of a right valve, drawn without the beak 

 so as to show the entire hinge, i, hinge of specimen shown in figure c and d. j, original type of C. 

 germana, restored; hinge of same figured on plate xl. h, interior of two left valves of C. grandis var . 

 intermedia, n. var.; Trenton, Haynie's Mill, Tennessee. 



