GO PROCEEDINGS OF WASHINGTON MEETING. 



specimens of Leperditia (L. angelini), Platyschisma hdicites, Sow., and small scales of 

 fishes mostly belonging to the genus Ceelolepis of Pander. 



With us the Eurypterus horizon forms the base of our uppermost Silurian stage, 

 K, according to my arrangement of our Russian Baltic Silurian in Estonia and the 

 island of Oesel,* and can be followed all over the island, from west to east, at the 

 boundary line between the stages J and K, the former corresponding to the Wenlock 

 of England and the Niagara limestone of North America. 



The Eurypterus beds are overlain by a yellow limestone or dolomite containing 

 Stromatopora, Favosites, Syringopora reticulata, Labechia conferta, and other corals (but 

 not Halysites, which is restricted entirely to lower horizons of the Upper Silurian), be- 

 sides Murchisonia cingulata and allied forms, Orthoceras inibricaium, <>■ angulatum, and 

 (). (jiijmitiii, Ilionin prism, Megabmus gothlandicus, Meristella didyma, Leperditia grandis, 

 and other fossils. In the southern and southwestern portions of Oesel there fol- 

 lows a band of gray limestone with Atrypa prunum, Spirifer elevatas, Chonetes stria- 

 tella, numerous specimens of Tentaculites and Beyrkliia, peculiar forms of Galymene and 

 Proetus, and in some places with a profusion of spines ( Onehus) and scales ( Tachylepis, 

 Pand., or Ghelodus, Murch., Oniscolepis) of fishes described by Pander in 1856. This 

 gray limestone, which is known among the northern German erratic bowlders as 

 the Beyrichia limestone, I regard as the highest beds of Oesel, though actual super- 

 position has not been observed. Both the gray and the yellow limestones corre- 

 spond very well with the Ludlow of Great Britain. The yellow limestone containing 

 also Eurypterus fischeri is very clearly recognized on the eastern side of the Swedish 

 island of Gothland, near < testergarn, and also on the Dniester in Podolia (southern 

 Russia), from which locality the Eurypterus fischeri was originally described. 



With regard to my Silurian country of Oesel, I have no reason to enter into the 

 Hercynian question, because, as already stated, our uppermost Silurian strata cor- 

 respond exactly to the typical Ludlow of England. Our Silurian is unconformably 

 covered by the middle Devonian (" Old Red sandstone "), since in the east the 

 Cambrian and lower Silurian strata are situated directly below the "Old Red 

 sandstone," just as in the west they lie below the upper Silurian deposits. 



The purpose of this communication is to attract the attention of American geol- 

 ogists to the striking resemblance of the fauna of our Baltic Eurpterus beds to the 

 Waterlime fauna of North America, and to express the hope that our cephalas- 

 pidean fishes, or something like them, would be some time found in this country. 



In coming to America it was my wish to become more intimately acquainted 

 with the different Silurian stages, and especially with those adjacent to the Water- 

 lime group. ;'. e., with the Onondaga and Guelph limestones on the one side and 

 the Tentaculite limestone on the other. It would perhaps be possible to find other 

 connecting links in the development of life in both countries. 



Lately I have had the opportunity of seeing the Waterlime and the Tentaculite 

 limestone at Oriskany falls in the state of New York. Both deposits together cor- 

 respond very well to our uppermost eastern Baltic stage A'. But, beyond this strik- 

 ing resemblance of the Waterlime crustacean fauna and thatof our Eurypterusbedst 

 I cannot yet compare strictly the other deposits of my uppermost Silurian zone in 

 this country. That will perhaps he possible after returning from our long excur- 

 sion, when I shall have perhaps the opportunity of seeing more of the Silurian 

 strata in the United States and Canada. 



*See Quar. Jour. Geol. Soc, Nov., 1882, p. o!4. 



