246 bulletin: museum of comparative zoology. 



formations may in former times have extended across this north- 

 em region. In DalecarUa, however, which is well to the north, 

 the Trinucleus shales are well developed, and contain the t\'pical 

 southern fauna. The Kegel and Wesenberg are certainly older than 

 the Trinucleus shales. 



The Chasmops limestone of Sweden has been little studied except 

 for the work of Olin on the trilobites in Scania, and the time is not yet 

 ripe for accurate correlations. The Upper Chasmops or Macrourus 

 limestone of Dalecarlia contains such species as Chasmops maxima 

 Schmidt, found in Russia in the Jewe and Kegel, while the lower 

 Chasmops limestone of the same region contains such t^'pical Kuckers 

 and Itfer fossils as Echinosphaerites aurantium, Chasmops odini, and 

 OxopJccia dorsata. The Chasmops limestone is therefore correlated 

 as indicated bv these fossils. As mentioned above, there are certain 

 trilobites which serve to connect the Chasmops limestone with the 

 shales in Scania containing Dicranograptus clingani and Pleurograptus 

 linearis. Between the zone of Nemagraptus gracilis and that of 

 Dicranograptus clingani, there is, it seems, a considerable gap, so that 

 the section in Scania is far from complete. 



Zone of Dicranograptus clingani. 



In southern Sweden the zone of Xemagraptus gracilis is succeeded 

 by the zone of Dicranograptus clingani, or as it is sometimes called, 

 the Middle Dicellograptus beds. 



These beds, have recently been studied in great detail on Born- 

 holm, politically an apanage of Denmark, but geologically in the 

 Scanian province. Hadding (61) has recognized four subzones on 

 this island. These are in descending order: 



4 Zone with Climacograptus styloideus Lapworth. 



3. Zone with Dicranograptus clingani Carruthers. 



2. Zone with Amplcxograptus vasae (Tullberg). 



1. Zone with Climacograptus rugosus Tullberg. 



Among the fossils of zone 4 may be mentioned, beside the name 

 fossil, Glossograptus quadrimucronatus, Diplograptiis truncatvs, Dicello- 

 graptus pumilis, Leptograptus flaccidus macer, and inarticulate brachio- 

 pods. 



Zone 3 has a large fauna, including among others, Amplcxograptus 

 nasae, Climacograptus hrevis, Dicellograptus forschammeri, D. pumilis, 

 and Corynoides curius. There are also several inarticulate brachio- 

 pods and Dahnanella argentea. 



