. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . t of the United States. GENUS Mactra The mactras live in the sand near the margin of the water,often upon the exposed open coast. The mantle is open, exceptwhere it is fused to form the siphons. These are short andunited. The outer gill is dorsally directed; that is to say, it doesnot depend into the mantle cavity as does the inner gill, butprojects just the other way; it is also smaller than the inner foot is strong, bent, and tongue-shaped, and no doubt welladapted t
. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . t of the United States. GENUS Mactra The mactras live in the sand near the margin of the water,often upon the exposed open coast. The mantle is open, exceptwhere it is fused to form the siphons. These are short andunited. The outer gill is dorsally directed; that is to say, it doesnot depend into the mantle cavity as does the inner gill, butprojects just the other way; it is also smaller than the inner foot is strong, bent, and tongue-shaped, and no doubt welladapted to the rough life in the surf and the heavy, shiftingsands. The main characteristic of the mactra shell is theprominent triangular-shaped fossette, or cartilage plate, situatedinternally and just under the beaks. The shells are equivalve, and devoid of brightcolors or strikingsculptural the pallialline is plain, and thesinus well marked butnot deep. M. solidissima is one of the very com-monest, if not the com-monest large bivalve ofthe New England, LongMactra solidissima. Island, and New Jersey. PELECYPODS 447 beaches. It is covered with a thin brownish or straw-colored epidermi*,usually more or less worn away in adult specimens and wholly absent f r< mithe dead valves found upon the beaches. There is a fragile V-shaped car-dinal tooth, which is generally broken away in forcing open the valves ;the lateral teeth are long and thin, and striated on their receiving sur-faces. The length of this giant clam is from four to seven is the first shell the collector will find (north of Hatteras) when hegoes to an open, sandy beach. M. siniilis. A small variety of the species last described, of similaroutline, but less heavy and strong. Its range is from Hatteras south-ward to Braxil. Passing from New Jersey to Hatteras, Mactru soli-(liHxhnu diminishes in size, and after passing that faunal barrier theNorthern form is entirely replaced by this Southern va
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmarinea, bookyear1901
