The Lawrencian Formation, 



343 



B. undatum inhabits the Atlantic from Cape Cod northwards. 

 Fossil at Beauport, Montreal, and various other phices in Lower 

 Canada; also in Britain, Sweden and Russia. Name from 

 buccina^ a trumpet; undatus, waved. It is called a v)helh in 

 Britain. Our fossil is considered a variety. 



Fig. 9. 



Fig, 



10, 



Fig. 



11. 



Fig. 



9.- 



■Buccinum undatum. 

 Fig. 10. — Fusus carinatus. 

 Fig. 11. — Mytilus edulis. 



Fig. 10. Fusibs c«rma/w5, called also Tritonivm fornicatum,' 

 — Living in the Gulf of St. Lawrence, Arctic Seas, Greenland ; 

 fossil at Beauport. Fusus, a spindle; carinatus, carinated, in 

 allusion to the carinae or keel-like ridges that wind round the shell, 

 ascending spirally to the apex ; these are more conspicuous in 

 some specimens than in others. 



Fig. 11. My tills edulis. — Fossil at Beauport, Montreal, &c. ; 

 living abundantly in the seas of Europe and America. The mus- 

 sels, while living, are attached to rocks, sea-weeds, or other marine 

 substances, by a flexible ligament like a bundle of fine threads, 

 which issues from within outward, passing between the valves* 

 This organ is called a byss^is. Violent sickness is sometimes 

 occasioned in Britain by eating the animal of this shell at certain 

 seasons. There are 50 living and 80 fossil species. Some 

 palagontologists arc of opinion that the genus existed during the 

 Lower Silurian period. Mytilis, (Latin) a mussel ; edvJis, edible* 

 Fig. 12. — Terrehratula psittacea, or Rhynconella psitiacca, — 

 This little fossil is interesting, because although the catalogue of 

 tiie genus contains upwards of 250 species, ranging from the Lower 



