246 OUR COMMON BRITISH FOSSILS. 



The most abundant of these early genera of 

 mollusca, besides those already named, are — Patella 

 (the limpet, whose simple cone is an index of the 

 degree in which all univalve shells have been modi- 

 fied), Bellerophon (a " heteropod," or free-swimming 

 gasteropod), Natica (which has been in existence ever 

 since, and is still abundant in British seas), Mnr- 

 chisonia, Holopella^ Loxonema^ Cyclonema, Ophileta, 

 Orthonota^ Ambonychia^ Pterinea, Myacifes, Cardiola^ 

 Nitclea, etc. In the Middle Silurian rocks which crop 

 up about Eastnor, in the Malverns (a locality not 

 likely to be soon forgotten for its quiet beauty), one 

 bivalve. Nucha Eastnori, is common. Several small 

 quarries may be visited in Eastnor Park where these 

 fossils are to be obtained. Near Bronsil a large 

 species of Pterinea occurs. 



The Upper Silurian rocks almost everywhere yield 

 plenty of fossil mollusca. In the hardened Wenlock 

 shales about Llangollen, Cardiola interrtiptce is most 

 abundant ; the casts showing that the two opened valves 

 were not separated. The Ludlow beds in the quarry 

 on the side of the river opposite the picturesque old 

 castle, are crowded with Ctenodonta and Orthonota. 

 In the Wenlock limestone of Shropshire and South 

 Staffordshire that splendid fossil univalve Euomphahis 

 rugosiis is abundant. 



The Middle Devonian strata of North Devon 

 occur in about the most varied and picturesque 

 portion of that charming county. I have found a 



