404 BULLETIN 53, UNITED STATES NATIONAL MUSEUM. 



18198. Mickwitzia monolifera Schmidt. Plesiotype. 



Lower Cambrian. Lugnas. Sweden. 



Walcott, Tenth Ann. Rept. U. S. Geol. Surv., 1890, p. 704, pi. 70, 

 fig- 2g. 



456. Micrabacia americana Meek. Holotype and paratypes. 



Fox Hills (Cret.). Moreau River, South Dakota. 



Meek, Rept. U. S. Geol. Surv. Terr., IX, 1876, p. 1, pi. 28, figs, 

 ia, ib. 



38098. Microblattina perdita Scudder. Holotype. 



Coal Measures. East Providence, Rhode Island. 



Scudder, Bull. No. 124, U. S. Geol. Surv., 1895, p. 57, pi. 3, fig. 5. 



46048. Microceras minutissima Ulrich. Cotypes. 



Lorraine (Ord.). Cincinnati, Ohio. 



Ulrich, Journ. Cincinnati Soc. Nat. Hist., II, 1879, P- x 3> P 1 - 7> 

 fig. 8. 



18329. Microdiscus bellimarginatus Shaler and Foerste. 



Plesiotype. 

 Lower Cambrian. Conception Bay, Newfoundland. 



Walcott, Tenth Ann. Rept. U. S. Geol. Surv., 1890, p. 630, pi. 81, 

 figs. 2a-2b. 



17449. Microdiscus connexus Walcott. Cotype. 



Lower Cambrian. Near Salem, Washington County, 

 New York. 



Walcott, Amer. Journ. Sci. (3), XXXIV, 1887, p. 194, pi. 1, figs. 

 4, 4b; Tenth Ann. Rept. U. S. Geol. Surv., 1890, p. 631, pi. 



80, figs. 9~9b. 



18361. Microdiscus helena Walcott. Cotype. 



Lower Cambrian. Conception Bay, Newfoundland. 



Walcott, Proc. U. S. Nat. Mus., XII, 1889, p. 40; Tenth Ann. 

 Rept. U. S. Geol. Surv., 1890, p. 632, pi. 81, figs. 1, ia. 



15394. Microdiscus lobatus (Hall). Plesiotype. 



Lower Cambrian. Troy, New York. 



Walcott, Bull. No. 30, U. S. Geol. Surv., 1886, p. 156, pi. 16, figs, 

 i-ib; Tenth Ann. Rept. U. S. Geol. Surv., 1890, p. 632, pi. 



81, figs. 4-4b. 



15396. Microdiscus parkeri Walcott. Cotype. 



Lower Cambrian. Parker's Quarry, Georgia, Vermont. 



Walcott, Bull. No. 30, U. S. Geol. Surv., 1886, p. 157, pi. 16, figs. 

 2, 2a; Tenth Ann. Rept. U. S. Geol. Surv., 1890, p. 632, pi. 

 80, figs. 7~7a. 



15397. Microdiscus speciosus Ford. Plesiotype. 

 17478. Lower Cambrian. Trov, and Washington Count}', New 



York. 



Walcott, Bull. No. 30, U. S. Geol. Surv., 1886, p. 154, pi. 16, fig. 

 3c; Tenth Ann. Rept. U. S. Geol. Surv., 1890, p. 632, pi. 

 Si, figs. 5-5C 



