306 bulletin: museum of comparative zoology. 



18. Subulites subulus W. 



19. Worthenia esthona Ku. I. 



20. silurica V. E. Ku. I. J. K. W. 



21. Arges wesenbergensis W. 



22. Cybele brevicauda W. 



23. Encrinurus multisegmentatus W. 

 21:. seebachi \V. 



25. Homolichas eichwaldi (not certain as to its occurrence below). 



26. Illaenus linnarssoni W. 



27. roemeri W. 



28. Prionocheilus pedolobum W. 



29. Sphaerexochus angustifrons W. 



This is about fifteen per cent of the Lyckholm fauna, but several 

 of the species are long ranging and, hence, have no stratigraphic value; 

 most of the gastropods and some of the other forms are said to be 

 varietally different, and in the case of a few {Cyclocrinites spasski) 

 the identifications are uncertain. The number of common species of 

 chronologic value, therefore, becomes small, and these must probably 

 be looked upon as survivals from the older stage, as similarly occurs 

 in the Richmond of America, and the difference between the Lyckholm 

 and Wesenberg faunas argues for a time break of considerable impor- 

 tance, but one that does not appear to be of systemic value. 



Borkhohn formation. The eastern limits of this formation are near 

 Lake Peipus, the strata making their first appearance at the surface 

 near Pastfer and Miintenhof. Thence the outcrops of the formation 

 extend westward over a narrow band just south of the 59th parallel. 

 A few exposures, as the Nyby outlier, occur in Lyckholm territory. 

 Except for the little island of Wohhi to the east of Dago,^ the forma- 

 tion does not appear to have been noted on the islands. The divi- 

 sion is probably not over twenty feet thick. The type-locality is in 

 the park at Borkhohn, the estate of Herr von Rennenkampf. The 

 type-exposure is in a quarry, now no longer worked. According to 

 Schmidt, there were formerly about fifteen feet of strata shown; 

 but the present exposures are probably not so good as in earlier days, 

 since little more than twelve feet are now uncovered and few fossils 

 other than corals are obtainable. 



The lowest beds are said to consist of a crinoidal limestone with a 

 thickness of about a foot. Above this lies a coarse-grained, yellowish 

 gray and white limestone which appears to contain few fossils other 



1 Schmidt. Bull. Acad. sci. St. Petersb., 1881, ser. 7, 30, no. 1, p. 39. 



