176 



Cape Cod will account for its slower dispersion along the 

 Connecticut shores. 



It seems somewhat remarkable that this mollusk, for so 

 many years an inhabitant of Nova Scotia and the Bay of 

 Chaleur, should have been so long finding its way to the 

 State of Maine. As far back as 1855, I received speci- 

 mens of this species from Bathurst in the Bay of Chaleur. 



The conditions are evidently very favorable for its ex- 

 istence along our shores, for it has increased in countless 

 numbers, and the species seems to be fully as robust, and 

 oftentimes exceeding in size its relatives in Europe. 



Mr. Gray calls attention to the fact that this species, 

 known under the common name of "periwinkle," forms an 

 abundant supply of food to the poorer classes in Great 

 Britain and Ireland, and there is no reason why the 

 poorer classes here should not avail themselves of a mol- 

 lusk so easily obtained. 



Believing that, in past times as at present, the dispersion 

 of forms took place in similar ways, it is interesting to 

 look ahead to a time when the present mud and sand of 

 the shores shall have been converted and consolidated 

 into stratified rocks with the species entombed in a fossil 

 condition. We may imagine a future Barrande finding 

 material for an onslaught on the derivative theory by 

 pointing to the abundant occurrence of this species in a 

 narrow bed of rock of the same horizon and occurring 

 over hundreds of miles of territory, when the beds just 

 below reveal no vestige of this large and vigorous spe- 

 cies. 



Littorina litorea, Linn, 



