EARLY PALEOZOIC BEYOZOA OP THE BALTIC PROVINCES. 15 



C3. Itfer heds. — In the vicinity of Itfer, north of Wesenberg, in 

 Esthonia, a hard limestone 20 to 30 feet in thickness, bearing siliceous 

 concretions, succeeds the shaly Kuckers zone and forms a passage 

 bed to the richly fossiliferous Jewe formation. Although the 

 described species are less numerous, the fauna of these Itfer beds is 

 essentially the same as in the other members of division C. Only one 

 bryozoan from these Itfer beds, Batostoma granulosum, has come to 

 my notice. 



Dl . Jewe limestone. — ^Very fossiliferous, impure limestone and shale, 

 averaging 100 feet in thickness, compose formation D, in which three 

 divisions are recognized by the Russian students, (1) a lower zone of 

 siliceous limestone and shales well exposed near Jewe and termed the 

 Jewe limestone, (2) more shaly strata known as the Kegel beds, and 

 (3) very fossiliferous thin-bedded, blue limestones and shales well 

 shown at Wassalem, whence they derive their name. The species of 

 these three divisions are much alike, and likewise are quite similar 

 to many of the forms in formation C. 



The cystids, trilobites, and gastropods are the only groups of Dl 

 which have hitherto received detailed study. The collections of 

 bryozoans from the Jewe limestone were not very extensive, but they 

 showed 29 species, of which 8 are identical with American Middle 

 Ordovician forms. 



D2. Kegel heds. — ^The shaly strata making up this division have 

 received probably less study than the Jewe limestone, judging from 

 the list of described species, but from a few samples before me, I should 

 judge the fauna to be a large and varied one. A fragment of lime- 

 stone less than half a cubic inch in size, preserved only for a trilobite 

 head upon it, was found upon thin sectioning to contain no less than 

 9 species of Bryozoa. This fragment and a few additional specimens 

 afforded the 12 species of Kegel bryozoans noted in this paper. 



D3. Wassalem beds. — The thin-bedded, blue, argillaceous limestone 

 and shale of this division is the most fossiliferous of all the Russian for- 

 mations as far as bryozoans are concerned. Some of the layers are 

 literally one mass of these organisms, as is evident from plate 13, 

 which represents the surface of one of the thin limestone layers. 



The preservation of the specimens from D3 is most beautiful on the 

 exterior, but the interior is sometimes destroyed by a form of dolomi- 

 tization. Similar conditions of preservation prevail in the Ordovician 

 (Decorah shales) bryozoans of Minnesota, and the lithologic resem- 

 blance of the strata comprising the Russian division D3 to these 

 American beds is most striking. This lithologic similarity is borne 

 out in the bryozoan faunas of the two areas, for of the 43 species now 

 known from the Wassalem, 26 are American Middle Ordovician forms. 

 A glance over the table on page 50, giving the list of species with their 

 distribution, will show the large percentage of typical Black River 



