342 Canadian Record of Science. 



Charles Lap worth in many places in his " Geological 

 distribution of the Bhabdopora," recognized Bryograptus as 

 older than the Dictyonema shale, 1 but Dr. W. C. Brogger 

 disputes this, and says that in Scandinavia that genus 

 appeared above the Dictyonema beds. He cites three species 

 which appeared very soon after Dictyonema, and one of 

 these is referred by Hermann to Trichograptus. 



Our observations in the St. John basin favour Lap- 

 worth's views, as we find a Bryograptus mingled with the 

 earliest examples of Dictyonema, and below the proper 

 Dictyonema beds. 



Dictyonema flabelliforme ranges through a greater thick- 

 ness of beds in Acadia than it does in Sweden or Norway, 

 and perhaps for this reason, has a greater variety of 

 Brachiopods and Trilobites associated with it than are 

 found in these countries, or indeed any where else. In- 

 cluded in the beds where Dictyonema is found, there are 

 trilobites belonging to Angelin's genus Leptoplastus and 

 to Agnostus. Parabolina cf heres Brogg, and Protopetura cf 

 acanthura, Ang., also occur, and as the fossil is found about 

 fifty feet lower down than the bed where these trilobites 

 occur, it may even reach the zone of Parabolina spinulosa, 

 Wahl. But the Dictyonema of these lower layers is a bushy 

 form like var. confertum of Sweden. 



Only one trilobite is mentioned as occurring in Sweden 

 in the Dictyonema beds. This is Angelin's species Acerocorne 

 ecorne, a species resembling Peltura scarabeoides, but posses- 

 sing a pygidium devoid of spines. J. C. Moberg has thrown 

 doubt on the occurrence of even this one trilobite in the 

 Dictyonema beds. He mentions that it is said to have been 

 found at Sandby in Scania where Protopeltura acanthura 

 occurs, and it is thus possibly with fossils somewhat older 

 than the true Dictyonema beds. Further, it may be added 

 that Linnarsson says the Dictyonema beds in Scania contain 

 (beside their characteristic fossil) a species of Dichograptus 

 in great numbers, and that in that province a " transition 



1 Die. Silurischen Etagen 2 und 3, p. 37. 



