810 BULLETIN 92, UNITED STATES NATIONAL MUSEUM. 



Mitroceras gebhardi (Hall). 



Trochoceras gebhardii Hall, Pal. New York, 2, 1852, p. 335, pi. 77, fig. 2; pi. 77a, 



figs, la-d. Grabau, Bull. Geol. Soc. Amer., 11, 1900, p. 371, pi. 21, figs. 3a-b; 



Bull. New York State Mus., 45, 1901, p. 217, fig. 149; ibid., 92, 1906, p. 110, 



figs. 16, 17; Michigan Geol. Surv., Geol. Ser., 1, 1909, p. 199, pi. 31, figs. 3a-b. 

 Mitroceras gebhardi Grabau and Shimer, N. A. Index Fossils, 2, 1910, p. 75, figs. 



1289, 1290. 

 Cayugan: Schoharie (Cobleskill), Buffalo and Williamsville, New York (Akron). 



MITROCRINUS Miller and Gurley. Genotype: M. wetherbyi Miller and Gurley. 

 Mitrocrinus Miller and Gurley, Bull. Illinois State Mus. Nat. Hist., 5, 1894, p. 

 22. Miller, N. A. Geol. Pal., 2d App., 1897, p. 748. Bather, Treatise on 

 Zool., pt. 3, Echinoderma, London, 1900, p. 203. 



Mitrocrinus wetherbyi Miller and Gurley. 



Mitrocrinus wetherbyi Miller and Gurley, Bull. Illinois State Mus. Nat. Hist., 5, 



1894, p. 22, pi. 2, figs. 4-6. Miller, N. A. Geol. Pal., 2d App., 1897, p. 748, 



fig. 1364. 

 Chazyan (Ottosee): Knox County, Tennessee.' 



MODIOLA OBTUSA Hall. See Modiolopsis obttisa. 



MODIOLODON Ulrich. Genotype: Modiolopeis oviformis Ulrich. 



Cyrtodonta (part) Safford, Geol. Tennessee, 1869, p. 287. 



Modiolopsis (part) Ulrich, Amer. Geol., 5, 1900, p. 276. 



Modiolodon Ulrich, Geol. Minnesota, 3, pt. 2, 1894, p. 521; Geol. Surv. Ohio, 7, 

 1893, p. 652. Cumings, 32d Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1908, 

 p. 981. Grabau and Shimer, N. A. Index Fossils, 1, 1909, p. 516. 



Modiolodon arcticus Schuchert. 



Modiolodon arcticus Schuchert, Proc. U. S. Nat. Mus., 22, 1900, p. 161, pi. 13, 



figs. 18, 19. 



Trenton: Head of Frobisher Bay, Baffin Land. 

 Holotype.C&t. No. 28166, U.S.N.M. 



Modiolodon declivis Ulrich. 



Modiolodon declivis Ulrich, Geol. Surv. Ohio, 7, 1893, p. 654, pi. 53, figs. 3 and 4. 

 Cumings, 32d Ann. Hep. Dep. Geol. Nat. Res. Indiana, 1908, p. 1005, pi. 

 46, figs. 2, 2a. 



Richmond (Whitewater) : Richmond, Indiana. 

 Holotype.C&t. No. 46227, U.S.N.M. 



Modiolodon ganti (Safford). 



Cyrtodonta Gantii Safford, Geol. Tennessee, 1869, p. 287, pi. 1 (E), figs. la-h. 

 Modiolodon Gantii Ulrich, Geol. Minnesota, 3, pt. 2, 1894, p. 521, fig. 40d. 

 Cypricardites ganti Miller, N. A. Geol. Pal., 1889, p. 476 (gen. ref.). 

 Trenton (Hermitage): Wilson County, Tennessee. 

 Cotypes.Czt. No. 46228, U.S.N.M. 



Modiolodon(?) gibbus Ulrich. 



Modiolodon(?) gibbus Ulrich, Geol. Minnesota, 3, pt. 2, 1894, p. 522, pi. 35, figs. 

 28, 29. 



Modiolopsis gibba Miller, N. A. Geol. Pal., 2d App., 1897, p. 782 (gen. ref.). 



Black River: Near Cannon Falls, Minnesota (Decorah); Lincoln County, Mis- 

 souri (Auburn). 



Eolotype.Csit. No. 46229, U.S.N.M. 



