THE ECONOMIC MOLLUSCA OF ACADIA. 



107 



Habits. This is a well-marked shell and not like any other yet 

 -found on our coast. It is a bivalve, each valve of which is somewhat 

 like that of the Clam. Across the riiddle runs a furrow, in front of 

 which the lines of growth rise in regular teeth, which are entirely 

 wantini? behind that line. The shell gapes very widely open both before 

 and behind, and the dorsal margin in front of the furrow is folded over 

 outwards It does not exceed four inches in length in our waters, but 



Fig. 21. — Zirphcea crhpata. Natural Size. 



grows much larger to the south and on the west coast. It is a burrow- 

 ing Mollusc, and lives in hard clay, soft stone or even submerged wood. 



Economics. On the coast of California this species is 

 extensively eaten. It is, however, much larger than with 

 us, and is regularly exposed in the markets under the name 

 of "Date-fish." It is not abundant enough in Acadia to be 

 of any value. It appears to do no injury in its burrowing, to 

 any of man's works. 



27. Teredo navalis Linnaeus. 



[Teredo, a borer; navalis, infesting ships.] 



Ship -worm. 



Distribution. (a) General; — In submerged timber, 

 'Gulf of Mexico to Vineyard Sound. Gulf of St. Lawrence, 

 abundant. [Massachusetts Bay to Chedabucto Bay, much less 

 abundant]. Sweden and Great Britain to Sicily; Algeria and 

 the Black Sea. 



{h) In Acadia; — St. John, Shediac, Pictou, Whiteaves. 

 ^Northumberland Straits, St. George's Bay, Strait of Canso, 



