TWENHOFEL: EXPEDITION TO THE BALTIC PROVINCES. 303 



5. Lyellia bacillifera. 



6. Proheliolites dubius. 



7. Atrypa imbricata. 



8. Clitambonites sinuatus. 



9. verneuili. 



10. Dalmanella winiani. 



11. Orthis oswaldi. 



12. Platystrophia biforata lynx. 



13. Strophomena assmussi. 



14. semipartita. 



15. Chasmops eichwaldi. 



16. Isotelus robustus. 



17. Proetus ramisulcatus. 



Dr. Bassler from his fauna! studies of Baltic Russian strata stated 

 that it appeared very probable^ that a great time break exists within 

 the Lyckholm formation, and " that the Wesenburg and early Lyck- 

 holm show affinities with the early Trenton, and that the upper 

 Lyckholm and Borkholm closelv resemble certain divisions of the Rich- 

 mond group." ^ He describes the Lower Lj'ckholm as a "Magnesian 

 limestone holding jNIaclurea, Subulites and other gastropods related 

 to American Trenton species"- and "The bryozoans of the lower 

 Lyckholm are, like those of the American Galena, distinctly Trenton 

 in character." In his table of correlation he places the Lower Lyck- 

 holm as the equivalent of the Stewarts ville dolomite of the Mississippi 

 Valley.^ In drawing his conclusions Bassler labored under the 

 extreme difficulty of never having seen the strata in the field and he 

 also had to accept the statements on the labels attached to the speci- 

 mens which he studied. 



Born^ dissents from the conclusion of Bassler relating to a time 

 break in the Lyckholm and denies its existence. He also disagrees 

 with Bassler on the correlation of the Lyckholm; but as he fails to 

 definitely state its stratigraphic equivalent in the American section, 

 referring it to two possible horizons, this objection need not be further 

 considered. Schmidt^ described the Lower Lyckholm as a white, 

 thick-bedded limestone, rich in silica and carrying few corals; while 



1 Bassler. Bull. 77, U. S. N. M., 1911. 



2 Bassler. Loc. cit., p. 9. 



' Bassler. Loc. cit., p. 17, 38. 



' Born. 1913, Centralbl. min., geol., pal., 1913, no. 22, p. 714-19. 



• Schmidt. Mem. Acad. sci. St. Petersb., 1881, ser. 7, 30, no. 1, p. 37. 



