28 Murchisons Silurian System. 



interest as links connecting the lower new red sandstones 

 with strata of the same age in the north of England, which 

 are known to geologists through the labours of Professor 

 Sedgwick. Among the shells from the marls at Colyhurst 

 Professor Phillips recognises Axinus obscurus, or a large 

 variety of that species, as the most prevalent, associated with 

 an avicula, not very remote from A. sociales, and many small 

 undescribed univalves. 



" Having now described the three upper divisions of the 

 series in those districts where their characters and order of 

 super-position are distinct, I might at once proceed to the 

 examination of the subjacent sandstones where they are 

 most expanded, as around the coal fields of the central 

 counties. It is desirable however previously to invite atten- 

 tion to the prevailing characters of the lower portion of the 

 system in Gloucestershire and the west of Worcestershire, 

 where being little more developed the whole of its lower por- 

 tion consisting of conglomerates and sandstone is so intimately 

 connected that they can be considered only under one head." 



The members composing the bottom of the system are oc- 

 casionally difficult to identify in different localities, as their 

 characters are mixed, sometimes calcareous, at others quart- 

 zose, and occasionally containing a great abundance of peb- 

 bles and fragments of trap rock, intermixed with sedimentary 

 rocks of great antiquity. 



Having traced the line of demarcation between the New 

 Red Sandstone and the older rocks on which they rest, " I 

 commence by pointing out the manner in which from small 

 beginnings in the south their successive development is ac- 

 complished as we proceed northward. At Huntley soft red 

 sandstones first appear rising from beneath the marls, and 

 separating them from silurian rocks ; and between that 

 place and Newent, where the sandstone attains a consider- 

 able thickness, there are traces of quartzose conglomerates 



