PHYSICAL AND CLLMATAL CONDITIONS. i;^,9 



abuiidiuit on the coasts of I'rinpe Edwiird island ami 

 northern New lirunswiek, the Quahog or Wanipnni shell, 

 the Pctricola jihohuJiforinis, which, ahjn^n' with Zlrfca 

 vri^ipatd, l)urro\vs everywhere in the soft sandstones and 

 shales; the lu-iiutiful Modiolu idira' uln, forming tlense 

 mussel-I)aid<s in the sheltei'ed coves and estuaries: 

 Cifilu'rea {CdllUlu) conrcxa ; Cochlorh'siiia leana and Ciim- 

 mivgia tcUinoidoi ; Cn-pul h fa foniinif.a, the sli|)])er-lini])et, 

 and its variety Kni/niforniis, swarmin_L( especially in the 

 oyster h(Mls: JV(i!^s(( ohfialrf a and Biariiium cinereinit, with 

 many others of similar southern distribution. Xor is 

 the fauna so very meanre as inight be supposed. My own 

 collections from Xorthiimberland strait inidude about 

 fifty sj)ecies of mollusks, and some not possessed by me 

 have been found by Mr. Whiteaves. Some of these, it is 

 true, are northern forms, but the majority are of New 

 England species. 



The causes of this exceptional condition of things in 

 the Acadian l»ay carry us far back in ge(dogical time. Tiie 

 area now constituting the gulf of St. Lawrence seems to 

 liave been exemi)t from the great movements of ])lication 

 and elevation which pro luced the hilly and metamorphic 

 ridges of the east coast of America. These all die out 

 and disappear as they a])pr()ach its southern shore. The 

 tran([uil and gradual passage from the lower to the u[)per 

 Silurian ascertained l)y l^illings in the rocks of Anticosti, 

 and uniipK! in North America, furnishes an excellent 

 illustration of this. Tn the Carb(jniferous period the gulf 

 of St. Lawrence was a sea area as now, but witii wider 

 limits, and at that time its southern part was much tilled 

 up with sandy and muddy detritus, and its margins were 

 invaded by beds and dykes of trap[)ean rocks. In the 

 Triassic age tiie red sandstones of that period were 



