129 



Valves of Lingulepis Gregwa from Assise E. 1 d., at Boundary brook. 



Dimensions 

 &c. of valves 

 from Bound- 

 ary brook. 



The variation in the form of the valves in those two tables is, in many 

 cases, due to the distortion of the valves after entombment. 



If the remarks on orientation in an earlier part of this report be referred 

 to, it will be seen that more than two thirds of the valves of this species 

 both at Boundary brook and Dugald brook have been affected by orienta- 

 tion, and as this orientation is lengthwise of the valley of Indian brook 

 of which these brooks are tributaries, that proportion of the ventrals are 

 elongated beyond their natural form. In this table the ventrals average 

 a third greater than their length ; but they have been subject to the 

 influence above referred to, and it may be assumed that in the original 

 relation of form the length did not exceed the width by more than a 

 quarter. 



To this cause are traceable most of the extreme elongation of valves ; Remarks on 

 but that there was a considerable variation naturally, is seen because tables, 

 valves oriented in the same direction show variation in comparative width 

 and length. The length and width of the dorsal valve are so nearly 

 equal that the effect of distortion and variation of form from biological 



9 c. R. 



