340 The Lawrencian Formation. 



here a bed about ten feet in thickness composed of nothing but 

 shells of Saxicava rugosa^ with scarcely any earth intermixed. 

 It reposes upon other beds containing a number of other species 

 in a deposit of gravel, with small boulders. The place may be 

 found by going to the mill at Beauport and proceeding up the 

 creek about 300 yards, where the cliff will be seen nearly white 

 from the profusion of the shells it contains. 



Professor Forbes says : " It occurs in all the Irish, Scotch, and 

 English fossiliferous drifts and glacial clays," and in the upraised 

 lands of Sweden it is also abundant, in association with other 

 species found with it in Canada. Saxicava — Latin, " saxum" 

 stone, and " cava^'' to excavate ; " rugosa,'' rough. 



Fig. 2. Tellina Groenlandica. — This little shell occurs in nearly 

 all the localities of Saxicava rugosa. It is at present living in 

 Arctic seas, and according to Capt. Bayfield, in the Gulf of St. 

 Lawrence. The generic name is from the Greek, " telline" a kind 

 of mussel. It is said that there are 200 species of Tellina living, 

 and 130 fossil in all the formations from the oolite upwards. 



Fig. 3. Tellina calcarea. — Living in the Arctic seas, Behring's 

 Straits and Greenland ; fossil at Beauport, Montreal and numerous 

 other localities in Canada, also in Scotland and Russia. Calcarea, 

 (Latin,) pertaining to lime. 



Fig. 4. Mya truncaia. — This is a thick strong shell, easily 



recognised by the abrupt truncation of one of its extremities. One 



of the valves has on the inside, immediately beneath the umbo, a 



remarkable projection called the cartilage process. There is 



another species, Mya arenaria, about the same size, but not 



truncated, also found fossil in Canada. " The Myas frequent soft 



bottoms, especially the sandy and gravelly mud of river mouths ; 



they range from low water to 25 fathoms, rarely to 100 or 125 



fathoms. Mya arenaria burrows a foot deep ; this species and 



Mya truncata are found throughout the northern and Arctic seas, 



from Ochotsk and Sitka to the Russian Ice Meer, the Baltic, and 



British coast ; in the Mediterranean they are only found fossil. 



They are eaten in Zetland and North America, and are excellent 



food. In Greenland they are sought after by the walrus, the 



Arctic fox and birds."* Both these species are living in the 



Gulf of St. Lawrence ; fossil at Beauport, Montreal, (fee. 



Mya^ a mussel ; truncata, cut off ; arenaria^ pertaining to sand. 



* Woodward's Recent and Fossil Shells, page 3 IV. 



