REPORT ON THE TESTACEOUS MOLLUSCA. 247 



(3.) 



COMPARATIVE TABLE OF OCCURRENCE OF THE 



SPECIES. 



Explanation. 



a. abundant, c. common, r. rare. i. only occasional individuals. 

 D. dead shells, l. living. + occurrence only. 



Menai Straits, Bridges to Penmaenmawr. — Dr. T. Alcock, 

 R. D. D., and A. O. Walker. 



North of Puffin Island, Redwharf Bay. — Prof. E. Forbes, 

 British Marine Zoology, British Association, 1860, 

 and R. D. D. 



Liverpool,* including Dee Mouth. — Mr. Byerley, Literary 

 and Philosophical Society of Liverpool, Proceedings, 

 viii, 1853-4. Mr. T. J. Moore, Mr. F. Archer, and 

 others. 



Formby and Southport. — Mr. C. B. Brown, in Dr. Nichols' 

 Southport, 1861, and Naturalists' Scrap Book, 

 Liverpool. Dr. Alcock and R. D. D. 



Blackpool and Fleetwood. — R. D. D. 



Isle of Man (South). — Prof. Herdman. 



Isle of Man (North). — Prof. E. Forbes, Malacologia 

 Monensis. 



Glacial Drift. — Moel Tryfaen and Blackpool, from Mr. 

 Shone's paper. Geological Soc. Q. J., May, 1878. 

 Liverpool and Wirral, by Mr. G. H. Morton, F.Gr.S., 

 and from Mr. Reade's paper, Q. J. G.S., Feb., 1874. 



* The indication of frequency in the Liverpool column is not of 

 certainty, as Mr, Byerley's notes do not in every case deal with that 

 question. 



