CAMBRIAN ROCKS IN SOUTH SHROPSHIRE. 659 



(a). Evidence from fossils. — Most of the Shineton forms are new 

 specifically, and several new generically. The species which are of 

 geological value are the following : — 



Conocoryphe monile, Salter. 



This species closely resembles C. striata, Emmr., which is one of 

 the forms characteristic of Barrande's " Primordial zone," and is 

 truly typical of the genus. Conocoryphe proper is common in the 

 Lower Cambrian of St. David's and in the Potsdam Sandstone of 

 North America, but is not characteristic in newer formations in 

 Britain. It is one of the most ancient known forms of life. 



Olenus Salteri, Callaway, and 0. triarthrus, n. sp. 



This genus has not hitherto, so far as I am aware, been found 

 above or below the horizon of the Lingula-nags. These two 

 species are not typical Oleni, but are allied to some of Angelin's 

 subgenera, possessing characters found in Leptoplastus, Eurycare, 

 and Sphosrophthalmus ; but they cannot be located with either. 

 Angelin's subgenera are characteristic of his Regio A, which, what- 

 ever be the exact position to which it is finally assigned, is certainly 

 very low down in the earlier rocks. It is probably representative 

 of our Lingula-flags. 



Agnostus dux, n. sp. 



A form closely allied to certain Menevian forms of St. David's. 



Lingulella Nicholsoni, Call. 



Resembling L. lepis, Salt., of the Lower and Upper Tremadoc 

 of Portmadoc. 



Obolella sabrince, Call. 



Closely allied to 0. sagittalis, Salt., of the Menevian of St. David's. 



The above fauna has a very ancient facies, and, taken by itself, 

 would suggest an age anterior to the Tremadoc. 



Species of Theca and BelleropJion occur in the shales, and, though 

 not of decisive value, are forms which we should expect to find in 

 Cambrian rocks. 



Asaphus (Asaphellus) Homfrayi, Salt. 



An Asaphid with unforked labrum, common in the Upper Tre- 

 madoc of Portmadoc, and the only form in the Shineton Shales 

 (except perhaps a hydrozoan or two) which is not new to science. 



Asaphus (Platypeltis) Croftii, Call. 



An asaphoid form with entire labrum, but of a different type 

 from A. Homfrayi. The typical Asaphids are Cambro-Silurian ; but 

 the entire labra connect these two species with the older forms of the 

 family, such as Niobe. 



The majority of the above species have an older facies than the 

 Tremadoc ; but the abundant occurrence of an Upper-Tremadoc form 

 and of another Asaphid points in an opposite direction; and I 

 submit that the facts of the case, so far as the fossils are concerned, 

 will be best satisfied by referring the beds to the age of the Lower 

 Tremadoc. 



(b). Evidence from Correlation with rocks in other localities. 



Dictyonema-beds at Pedwardine. — About 25 miles to the south- 

 west of Shineton, there is a small exposure of shales at Pedwardine, 



