78 THE HAMILTON ASSOCIATION. 



true. They are much more likely to attract attention from Palseon- 

 tologists than from shell collectors. There is nothing very, striking 

 in their general appearance ; they are frequently mistaken for Turrets 

 or Screws also. We possess in this Dominion a fair share of fossil 

 representatives from the lower silurian upwards, and Dr. Spencer, 

 F. G. S., recognized Hall's Loxone77ialeda, U. S. A., as also occurring 

 in the local rocks of Hamilton. 



Perhaps it would be better here to produce specimens of the 

 spirals Tuj-ricuktes cerites, including the fresh water Potamides and 

 Melanias, also inhabiting fresh water lakes and rivers in the warmer 

 portions of the globe, than wearying my hearers by repeating 

 descriptions not universally accepted. It may be because some 

 minor point was omitted, by original investigation, or who boiled 

 down the knowledge they acquired in a form which conveys all the 

 information needed. 



More closely related than the foregoing are the Limpets Calyp- 

 trea (Bonnets) Fessurellidff Key-holes and Pattellidce (rock limpets). 

 Cuming mentions that on the western coast of South America he 

 found one of the latter a foot or 14 inches long, which was used by 

 the natives as a dish. The writer collected half a dozen empty 

 shells of an Acmea, a minute form of the family at Anticosti, the 

 brightest known to him, exceedingly pretty. He thinks it must be 

 well described already by Naturalists on this continent, although he 

 has seen it figured. Over 100 species of rock limpets have been 

 found fossilized. Some occur even in Lower Silurians. 



The Mefoptoma (Philips), classified by Woodward under the 

 head of Patella, appears to be more closely allied to the branch 

 called Bon/iets. The late Prof E. Billings, of the Dominion Geo- 

 logical Survey, figured and described several from Quebec and a 

 few also from the Hudson River rocks, Anticosti. Professor Grey 

 claimed a certain relationship existed between the limpet and coat- 

 of-mail shell {chiton). The posterior plate of the latter he con- 

 sidered homologous with Patella. The other plates appear like 

 portions of the anterior slope successively detached. 



The Dentalida, tooth shells, are also of much interest to 

 Palaeontologists. The ribbed species, D. Elephantitium, of the 

 Phihppines, is regarded as the type. The family had fossil repre- 

 sentatives even so far back as the Palaeozoic Age, before the carbon- 



