11 



The only other fossil observed in these beds is Lingula 

 spatulata (Vanuxem), which is not uncommon, and of 

 average size. 



The Styliolina Limestone.— This is a continuous stratum 

 from four to six inches thick, and of a somewhat concretion- 

 ary character. It forms the bed of the stream under the 

 bridge, and for the greater part of the distance fronting the 

 section. (Plate IV.). Its concretionary character is 

 brought out by the differential solution which it has under- 

 gone, an irregular undulating surface resulting. A part of 

 this is, however, original structure, as shown by the over- 

 lying shales which conform to it. Near the lower end of 

 this section the stream has cut down through this rock, 

 exposing it in its full thickness, together with the 

 "Conodont" limestone and a part of the underlying 

 Moscow shales. 



The Styliolina limestone is usually very compact, without 

 any appearance of crystalline structure. It is highly 

 argillaceous, giving off a strong clay odor when breathed 

 upon. This fact accounts for the great amount of solution 

 which the rock has suffered on the exposed surfaces. These 

 surfaces invariably present a dissolved appearance, which 

 is not unlike an artificially smoothened mass of moulding 

 clay, which still shows the finger marks upon it. This 

 solution has brought out in relief the contained organic 

 remains other than Styliolina and the otherwise smooth 

 surface frequently exhibits small projecting fragments and 

 joints of crinoid stems, black shining "conodonts" and 

 other minute organisms. This is especially true of the under 

 side of the bed, which thus exhibits a close relation to the 

 next underlying bed. The whole of the limestone is made up 

 of the exuviae of Styliolina fissurella (Hall) which frequently 

 are visible to the unaided eye. The shells lie in all positions, 

 a fact prominently brought out by thin sections. (Fig. i). 



