THE ECONOMIC MOLLUSCA OF ACADIA. 
107 
Habits. This is a well-marked shell and not like any other yet 
Tound on our coast. It is a bivalve, each valve of which is somewhat 
like that of the Clam. Across the middle runs a furrow, in front of 
which the lines of growth rise in regular teeth, which are entirely 
wanting 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 crispata. 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. 
(b) In Acadia; — St. John, Shediac, Pictou, Whit eaves. 
^Northumberland Straits, St. George’s Bay, Strait of Canso, 
