SILUEIAN OF TB.E LAKE-DISTEICT. 883 



Oeratiocaris Murchisoni West side of Troutbeck ; Quarry south 



of Ooldwell. 



Peltocaris anatina, Salt Eebecca Hill ; Quarry south, of Ooldwell. 



Phacops obtusicaudatus, var Quarry south of Ooldwell. 



Orthis? Quarry south of Ooldwell. 



Acroculia West side of Troutbeck ; Quarry south 



of Ooldwell. 

 Orthoceras primgevum, Forbes East side of Troutbeck ; Quarry south 



of Ooldwell. 

 O. tenuicinctum, Portl. Quarry south of Ooldwell. 



When we compare the fossils of the Ooldwell Beds with those 

 found by Prof. Hughes in the Coniston Grits of Helm Knot, Dent 

 (Mem. Geol. Survey, 98 1ST.E. p. 11), we see a strong correspondence 

 between the two lists. Moreover Phacops obtusicaudatus, which is so 

 very local in the Lake-district proper, being almost confined to a 

 single bedding plane, along which it may be traced for several miles, 

 is also recorded from the beds on the north side of Helm Knot. The 

 lithological resemblance of the Coldwell and Helm-Knot beds is at 

 once apparent on comparison — the lower beds on the north side of 

 Helm Knot, with Phacops obtusicaudatus and large Orthocerata, being 

 precisely similar to the Middle Coldwell Beds ; whilst the beds on the 

 S.W. side of the Knot, with Graptolites colonus and Oeratiocaris, are, 

 except perhaps in being slightly more gritty, extremely like the 

 Upper Coldwell Beds, having the same fossils, in the Lake- district 

 proper. This correlation will account for the small thickness of 

 Coniston Flags mapped on the east of the river Lune, as compared 

 with the flags of the west side. 



The following table shows the relation of the beds in the two 

 districts : — 



Windermere Sedbergh District, 



District. 



Coniston Grits —Upper Coniston Grits. 



/ f Upper =Beds S.W. of Helm Knot, beds of 



n i;i n r> a J High Hollins, &c. 



ConistonFlags-j Uoidweii Beas 1 Middle = Beds N. of Helm Knot. 



(_ Lower. If present at Helm Knot not exposed. 

 \ Brathay Flags = Coniston Flags (of Frostrow Fell &c). 



The list given by Prof. Hughes from Helm Knot includes only 

 the fossils from the S.W. side of the Knot, which belong exclusively 

 to beds referable to the upper division of the Coldwell Beds. The 

 beds equivalent to the Middle Coldwell Beds in the Windermere 

 district are, as shown in the foregoing paper, found on the north 

 side of Helm Knot, and the following list shows the identity of the 

 fossils : — 



Fossils of the Beds on the North Side of Helm Knot. 



Phacops obtusicaudatus, Salt. 



Orthis. 



Orthoceras tenuicinctum, Portl. 



Orthoceras subundulatum, Munst. 



O. bilineatum. 



Oycloceras. 



3n2 



