328 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
18. Rhipidomella hybrida (Sowerby). 
19. Plectambonites transversalis (Dalman). 
20. Spirifer crispus. 
21. Schuchertella pecten. 
22. Strophomena euglypha. 
23. Wilsonia wilsoni. 
24. Omphalotrochus funatus. 
25. sculptis. 
26. Cornulites vagans Schrenck. 
27. Tentaculites ornatus Sowerby. 
28. Orthoceras annulatum Sowerby. 
29. canaliculatum. 
30. Beyrichia klodeni. 
31. Acidaspis marklini Angelin. 
32. Bumastus barriensis. 
33. Calymene tuberculata. 
34. Cyphaspis elegantula Angelin. 
35. Encrinurus punctatus. 
36. Proetus concinnus osiliensis. 
37. Aulacodus obliquus Eichwald. 
Numerous crinoid stems and at least four additional species of 
Bryozoa are also present. 
Strata of this same horizon are said to make their appearance on 
the small island of Keinast between Oesel and Moon, and Schmidt 
reports Palaeocyclus porpita (Linné) and Caryocrinus ornatus Hall to 
have been collected there. It is extremely probable, however, that 
the latter identification is incorrect. Farther westward on Oesel at 
Surika Pank and Hundwa Pank, the lithology of the formation be- 
comes less dolomitic. As a consequence, fossils are better preserved 
and, among others, Schmidt notes the occurrence of Thecia swinder- 
nana Goldfuss, Eridophyllum rugosum Milne Edwards and Haime, 
Camarotoechia borealis (Schlotheim), Rhynchotreta cuneata (Dalman), 
and Leperditia baltica Hisinger. 
Oesel formation. This represents the Upper Oesel group of Schmidt 
and with it the Silurian of Esthonia ends. The surface exposures of 
the formation appear to be confined to the southwestern side of Oesel, 
but there is a possibility that it finds representation among the higher 
rocks of Moon. It appears to be a direct continuation of the St. 
Johannis formation and, since there is no appreciable variation of dip, 
the stratigraphic relations are considered conformable. Probably 
