191 I. No. 7. A NEW DOWNTONIAN FAUNA OF THE KRISTIANIA AREA. 



found in the Downtonian Sandstone l)y Kington and in Upper Ludlow 

 Shales and Passage Beds by Ludlow. The body in the Norvegian 

 form is more slender and more elongated than in the English one; the 

 eyes are much larger. 



Eurypterus sp. 



A specimen of a small KayijpierHS, found in the fish horizon prob- 

 ably belongs to a third species. The caudal spine in this one is much 

 longer and thinner than in the others previously mentioned. 



Pterygötas sp. 



A body segment from the fish horizon shows a typical Pterygotus 

 sculpture. A lamelliform appendage and different other fragments prob- 

 ably also belong to a Pterygotus. 



Merostomichnites sp. 



Trails probably made by Eurypterids are, as already mentioned 

 found in two horizons. They are found verj' abundantly especialh' in 

 the upper one: the same trails were also found in the section at the 

 highroad between Kroksund and \'ik by Til. MÜNSTER. 



Trails of a Crustacean. 

 In the section at the highroad between Kroksund and \'ik Th. 

 Münster also found an other small trail of a crustacean, that cannot yet 

 be determined more exacth'. Other m\-sterious impressions also occur here. 



Ostracoderm Fishes. 



Ceplmlaspidomorplii G( )0DRICM. 



Cephalaspidomorph fishes are quite common in the new fauna; two 

 forms are found, that differ considerably from each other in structure 

 and size. Both of them are new, and they represent two different 

 phases of development from the primitive Ateleaspidat' to the true 

 Cephalaspidae. 



The largest and most common of these new forms is somewhat 

 closelv related to AteJeaspis Traqu., but is more highly developed. 

 I present it as a new genus, and in consequence of the truncated dorsal 

 shield without cornua I have named it Ai:er((spi.<. It seems most natural 



