178 DEVONIAN FAUNA. 



Remarks. — This is undoubtedly the shell to which Davidson ultimately restricted 

 the name Ch. Hardrensis ; but its title to that name seems rather faulty. 



Ch. Hardrensis, though described in Phillips's Devonian work, seems primarily 

 to be a Carboniferous species, his two first and best figures being from Westleigh 

 (Culm) and Yorkshire, though he also quotes it from Berry Pomeroy and 

 Meadfoot. In 1852 M'Coy limited the name to the Carboniferous form, referring 

 the Devonian shells to Ch. sarcintdata (Schlotheim). Davidson, in 1865, united 

 under it both the Carboniferous and Devonian shells, quoting it as especially 

 abundant from near Barnstaple, figuring " one of Phillips's original specimens " 

 from North Devon, and uniting with it Lept&na sordida, Sowerby. In 1880, however, 

 in deference to the opinion of de Koninck, he reluctantly separated the Carboni- 

 ferous shell under the name Ch. Laquessiana, de Koninck, remarking at the same 

 time that the Rev. W. Downes had found two good examples of Ch. Laquessiana 

 at "Westleigh, which is Phillips's first locality for his Ch. Hardrensis. In face of 

 the latter fact, can Phillips's be superseded by a later name for the Carboniferous 

 shell, if it is distinct from the Devonian form ? But further, though possibly 

 Davidson may have included more than one species among the numerous Carboni- 

 ferous varieties which he records, some of them, including the typical Carboniferous 

 shape, seem impossible to be distinguished from our Pilton shells (at all events in 

 their present state of preservation). Lastly, it is also to be noted that the shell 

 which in 1882 he figures from Hope's Nose seems also to coincide with them. On 

 the whole it seems best to retain Phillips's name for these common Pilton shells, 

 only remembering that, if the Carboniferous shell be ultimately proved distinct, it 

 has a strong claim to retain the name Hardrensis for itself. 



As seen in the Pilton Beds our species is very variable. Its diversity in shape 

 is doubtless exaggerated by distortion, but its fine divaricating rays vary consi- 

 derably in size and number, while they have a granular appearance, and sometimes 

 show the characteristic arrangement of minute regular and close concentric 

 striae. The hinge-spines are only very imperfectly seen in any of our specimens, 

 but the slight indications of them occasionally visible seem to have the same 

 obliquity as in Phillips's type. 



