57 



Some small slabs were tested from Dugald brook from the same 

 assise as those above mentioned on Boundary brook. These show a 

 more decided orientation than the preceding : 



ORIENTATION in four small slabs Assise E. 1 d. 



Lingulepides 

 oriented in 

 Assise E. 1 d, 

 Dugald brook. 



The ventral valve is thicker and is more regularly conical in this 

 variety than in L. Gregwa ; these differences may have helped to give 

 this form a more pronounced orientation than the L. Gregwa type. 



Between the Gregwa shale and the top of Division 2 of the Etche- 

 minian, coarse sediments prevail; brachiopods are scarce and give no 

 data bearing on the orientation of the valves. But in some of the 



lower seams of Division 3, fossils are again numerous, and again show Acrothyra 

 , , _ oriented in 



the enect or the orienting current. Here a new fauna comes in, but Assise E. 3 a. 



at first sparingly. 



ORIENTATION of fossils on a small slab from Assise E. 3 a. 



