BALTIC REGION 591 



as well as casts of medusae and other fossils. This appears to be the 

 equivalent of the Mickwitzia sandstone of the Kinnekulle section. The 

 highest beds of the series consist of from 10 to 15 or more meters of an 

 unfossiliferous sandstone, the apparent equivalent of the Lingulid sand- 

 stone of Westergotland. There is thus clearly indicated a westward and 

 northward transgression of the Lower Cambric sea, with progressive over- 

 lap of the strata in that direction. 



Middle Cambric beds are wanting, but the Upper Cambric 25 is repre- 

 sented by the Ungulite sandstone, which is about 20 meters in thickness, 

 mostly unconsolidated, and characterized by Obolus apollinus. This 

 horizon is widely represented in Sweden by the Obolus conglomerate, 

 which in some sections (see Dalarne) lies at the base of the fossiliferous 

 series, and is there included in the Ordovieic, and in others (for example, 

 Oeland) lies on various members of the Middle Cambric, fragments of 

 which it includes. The Obolus is generally found in the cementing lime 

 sand, which in some sections includes also Dictyonema flabelliforme, 

 Agnostus pisiforme, and Olenus (Griinicken on CEland, Moberg, et al). 

 The Obolus conglomerate sometimes includes beds carrying Agnostus 

 pisiformis. 



We may judge from this that the Obolus conglomerate represents the 

 transgressing basal bed of late Cambric-early Ordovieic time, and that 

 the Dictyonema shale which follows it in CEland and in the Baltic Prov- 

 inces is the next depositional member. Bassler, in his section, indicates 

 a hiatus between the Ungulite and Dictyonema beds, but there seems to 

 be no evidence for such a break. When the Dictyonema shale is absent, 

 as at the Kinnekulle and in Dalarne, this may be due to non-deposition 

 of the shales, their place being taken by early Ceratopyge limestones. 

 Dictyonema flabelliforme was an Atlantic type, as shown by its abundance 

 on both sides of that ocean, especially in Britain and in eastern North 

 America. Ceratopyge, on the other hand, was a Pacific or Siberian type, 

 represented in America only in the western (Pacific) deposits. It is 

 thus perfectly possible that in different types of sediment at one and the 

 same period members from the faunas of distinct oceans may have become 

 buried, while the subsequent advance westward of the Ceratopyge fauna 

 may have resulted in the overlapping of the beds carrying this fauna 

 over the horizon of the Dictyonema fauna. It may be noted in this con- 

 nection that in parts of England (Malvern Hills) Dictyonema flabelli- 

 forme ranges through a thousand feet of strata, while in Sweden the beds 

 with Ceratopyge are as a rule of slight thickness. There are, of course,. 



25 Raymond includes this with the Dictyonema beds in his Packerort formation, which 

 he makes basal Ordovieic (p. 1S6). The presence of Ar/nostus pisiformis and Olenus, 

 however, argues against this. 



