W. H. Twenhofel — Silurian Section at Arisaig. 157 



33. "Very deep-green shales with a few thin lenticular bands 

 of limestone. Strike N. 58°-66° W. ; dip 40° W. 



Thickness _ - . 33 feet. 



34. Gray to bluish-green, rubbly more or less arenaceous- 

 argillaceous limestone in thick beds ; many of which are of a 

 lenticular character. In many places ripple marked and much 

 fractured and veined by quartz and calcite. In the lower beds 

 occur small black nodules. Strike N". 48° W., changing to 

 K 58° W. near the base ; dip 10° W. 



Thickness 342 feet. 



Fossils not common : Stropheodonta n. sp. 1, Leptcena rhom- 

 ooiclcdis, Ckonetes novascotica, Atrypa reticularis, Spirifer 

 subsulcatus (large), S. rugcecosta, Homceospira cf. evax. 



35. Fauna and beds of same character as in zone 34 except 

 that the ripple marking is more prominent and characterizes 

 the zone. Strike K 38° W. ; dip 38° W. 



Thickness 179 feet. 



36. Greenish-gray quartz-veined rubbly arenaceous-argilla- 

 ceous limestone in thick beds, and grayish-blue splintery flags 

 with some green and rusty-purple shale to the mouth of 

 McPherson's brook. Often ripple marked. Strike N. 50° W. ; 

 dip 40° W. 



Thickness ._.. 111 feet. 



Chonetes novascotica, Stropheodonta sp. 1, Atrypa reticularis, 

 Spirifer rugcecosta, Grammy sia acadica, Pteronitella venusta. 



37. Grayish-green arenaceous shales, argillaceous limestone, 

 and splintery grayish-blue flags. Much veined and ripple 

 marked. Strike K 50° W. ; dip 30° W. 



Thickness ._ ___ 67 feet. 



Pholidops implicata, Chonetes novascotica, Camarotcechia cf . 

 borealis (Davidson's fig. 224-26), Spirifer rugcecosta, Pter- 

 onitella venusta, Grammy sia, Calymene tubercidata, Homa- 

 lonotus daivsoni. 



38. Greenish-gray argillaceous limestone and shale with 

 grayish-blue flinty flags. All in thick beds and much veined 

 by quartz and calcite. Strike N. 57° W. ; dip 37° W. 



Thickness 110 feet. 



Many fossils. Chonetes novascotica, Camarotmchia cf. hore- 

 alis, Spirifer rugcecosta, S. subsulcatus, Homceospira n. sp. 1, 

 Comulites proprius (?), Calymene tuberculata, Orthonota 

 angulifera {{), many bivalves. 



39. Red and grayish-green shales, gray and red argillaceous 

 limestones, and bluish-gray splintery flags to the mouth of 



