322 bulletin: museum of comparative zoology. 



lie in colonies at various levels, in some places composing the whole 

 of the rock and in others only a few or none being present. 



The greater portion of the rock of the formation appears to be com- 

 posed of a yellowish white, fine-grained limestone which is only partly 

 crystalline; or a coarse-grained, quite crystalline, dolomitic limestone. 

 At some levels or localities there is also a little shale. Schmidt 

 (Loc. cit., 1882, p. 526) states that in the east dolomites prevail, 

 while in the west the lithology is one of coralline limestone. In a 

 general way this conclusion appears justified. Also, in the eastern 

 limits, either the upper beds of this formation, or the lower beds of the 

 succeeding, consist of unfossiliferous sandstone which Schmidt at first 

 considered Devonian; but he later learned that the sandstone is 

 overlain by the fossiliferous beds of the St. Johannis formation which 

 necessitated his referring the former to the Silurian.^ 



Addifer, the type-locality, is in the eastern area. The exposures are 

 in an old quarry which has recently been reopened. About ten feet 

 are shown of which the lower six feet are typical Pcniamerus cstonus 

 limestone. The brachiopods are not uniformly distributed, but occur 

 in patches and in these they are extremely abundant. Many are 

 silicified, but others show no microscopic trace of silica. Flint nodules 

 are verv abundant and nianv are several inches long. The floor of 

 the quarry is composed of a coarse-grained, quite crystalline, dolomitic 

 limestone. How thick this is, was not learned. The upper four feet 

 of the quarry section consist of a whitish yellow, fine-grained, partly 

 crystalline limestone, which, except for a few poorly preserved corals, 

 appears to be without fossils. It contains a few white flint nodules. 

 Near one of the barns about the residence of this estate a ditch has 

 recently been constructed, and in it the same sequence as in the quarry 

 is shown. 



East of the railroad station, Wochma, about fifteen miles from 

 Addifer, are the old quarries of Koksfer, and Arrosaar. They are 

 largely grassed over, but a few of the old dumps permit collecting. 

 The rock appears to be a coarsely crystalline dolomitic limestone. 

 Fossils seem to be rare, consisting chiefly of Halysites, Cyathophyllum, 

 Favosites, and Zaphrentis. Pcntamenis cstonus v^&s not seen. Many 

 yellow or brownish yellow flint concretions are present. These strata 

 are higher than those of Addifer. 



At Pajus, a few miles east of Addifer is a small exposure of about 

 five feet of soft yellow limestone containing no observed fossils, but a 



1 Schmidt. Loc. cit., 1881, p. 46. 



