14 BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



the lowest division, Cl, are a cephalopod, Orthoceras regulare Schlot- 

 heim, in the lower bed, Cla, and the concretionlike cystid Echino- 

 s'phentes distinguishing the upper part of the division, Clb. The 

 Ecliinos'pherites, E. aurantium, is an especially noteworthy fossil on 

 account of its abundance and wide distribution. In America a species 

 of EcMnospTierites that I am unable to distinguish from E. aurantium 

 is abundant at numerous localities in the Middle Ordovician rocks of 

 the Appalachian Valley and in the Kimmswick limestone of Black 

 River age in the Mississippi Valley. 



Trilobites, gastropods, cystids, and brachiopods are as numerous in 

 the Echinospherites limestone as in the underlying Ordovician forma- 

 tions, and are represented by essentially the same genera. A bryozoan 

 fauna of 23 species, of which 11 are new, is described in the following 

 pages. Of these 23 species, 6 are characteristic fossils of the Black 

 River group of North America. 



C2. Kuckers shale (BrandscJiiefer) . — Faunally, the bituminous 

 shales and thin-bedded limestones making up the several members of 

 division C2 are closely related to the limestone of Cl, although the 

 bryozoans and ostracods are developed in greater abundance both in 

 species and individuals. The thin bands of bituminous shales in C2 

 are often crowded with bifoliate and other delicate bryozoans (see 

 pi. 12), while the more solid zoaria of the trepostomatous Bryozoa 

 sometimes entirely compose the thin limestone layers. The strata of 

 this stage, which average from 30 to 50 feet in thickness, are well 

 shown at Kuckers, near Jewe, north of Lake Peipus, but the bryozoans 

 herein described from this formation come from other localities, prin- 

 cipally Baron Toll's estate, near Jewe, Esthonia. Most of the Kuckers 

 fossils are probably the best preserved of all from the Russian Ordo- 

 vician strata, but they have not received the detailed study given to 

 the faunas of other Baltic formations. 



A fauna of 46 species of Bryozoa was found in the collections from 

 the Kuckers, with 14 species common to Russia and the Black River 

 group of America. 



The ostracode fauna has been carefully studied by Bonnema,^ who 

 recognizes 34 species distributed among well-known American Middle 

 Ordovician genera, such as Primitiella, Tetradella, Ceratopsis, Cteno- 

 lolhina, Ulrichia, and Bollia. None of these is identified with Ameri- 

 can forms, although the species are in many instances closely allied. 

 Species closely related to these Kuckers forms occur in the underlying 

 and overlying Ordovician rocks in Russia, but they await description. 



The trilobites are less numerous than in the underlying strata, but 

 their genera are essentially the same. The recorded brachiopods are 

 few in species, but this portion of the fauna has not received especial 

 attention. 



1 Beitrag zur Kenntnis der Ostrakoden der Kuckersschen Schicht (C2), Mitteilungen aus dem Mineralo- 

 gisch-Geologischen Institut der Reichs-Universitat zu Gronongen, vol. 2, pt. 1, 1909. 



