21 



bevond the bank, frequently forming an overhanging shelf, 

 which in the course of time will break down, carrying with 

 it large masses of the overlying shale. (See Fig. b, Pt. V. ). 



About four feet of the Moscow shales are exposed near 

 the lower end of the section. The concretionary limcvstone 

 bed which capped the shale at Section 1, is here represented 

 bv a layer of scattered concretions which contain a few 

 fossils, principally Liorhynchus multicostus [YioW). About 

 a foot below this is a second layer of concretions, double in 

 many places, and more continuous than the upper one. The 

 shale between these two layers of concretions contains the 

 Schizobolus fauna, i.e. Schizoholus truncatus [YiaW), Lior- 

 hynchus tnulticostus (Hall) and Amhocoelia praeumhoriR 

 (Hall). The first of these is quite common and well pre- 

 served. Large individuals of the other two are common, 

 but the shells exfoliate so strongly that the original surface 

 characters are seldom preserved in the specimens obtained. 



About four inches below the lower bed of concretions, or 

 from fourteen to sixteen inches below the top of the Moscow 

 shales, occurs a band of pyrite concretions, some of which 

 are of considerable size.* They are highly impure, and when 

 oxidized show as a brown band in the cliff. L. multicostus 

 (Hall) occurs abundanth' down to the pyrite layer, after 

 which it becomes rare. Ambocoelia. praeambona (Hall) is 

 common, however, throughout the exposed portion of the 

 shale in this section. 



In the lower beds of this section a dwarfed form of 

 Spirifer tuUius (Hall) occurs, a species ^\hich, in this region, 

 appears to be wholly restricted to the upper Moscow shales. 

 Schizoholus truncatus ( Hall ) occurs occasionally, but fossils 

 on the whole, are rather uncommon. The characteristic 

 association, ho\vever, of three species restricted to the upper 

 Moscow shale, namely : Spirifer tuUius {HaW), Amhocoelia 

 praeumhona (Hall) and Schizoholus truncatus (Hall), 



*My attention was first called to this band and its persistence in the other 

 sections by Prof. I. P. Bishop. 



