. West American shells; a description in familiar terms of the principal marine, fresh water and land mollusks of the United States found west of the Rocky Mountains, including those of British Columbia and Alaska ... CHAPTER III OYSTERS AND SMALL CLAMS. Fig. 24 The shell shown inFigure 24 is foundalong the whole name is Monia mac-roschisma, Desh., thePearly Monia. It is alsoknown as Placuanomiaand Pododesmus. It be-longs very closely tothe oyster family, buthas decided will notice that oneof the valves is much smaller than the other, andthat it also has a large hole
. West American shells; a description in familiar terms of the principal marine, fresh water and land mollusks of the United States found west of the Rocky Mountains, including those of British Columbia and Alaska ... CHAPTER III OYSTERS AND SMALL CLAMS. Fig. 24 The shell shown inFigure 24 is foundalong the whole name is Monia mac-roschisma, Desh., thePearly Monia. It is alsoknown as Placuanomiaand Pododesmus. It be-longs very closely tothe oyster family, buthas decided will notice that oneof the valves is much smaller than the other, andthat it also has a large hole in the center, throughwhich you can see an oval muscle-scar with linesradiating from the center. The small valve israrely found, as it usually adheres to the rock,even after the death of the animal, while the up-per valve is torn off by the waves and washedashore. The outside of this upper valve is rough,and marked by irregular, radiating ridges; butthe inside is sometimes beautifully pearly, thegreen and purple tints being most common. Thereare two muscle-scars, the lower one of which isnot shown in the cut, but it is smaller and smootherthan the other. The shell is normally circular. OYSTERS AND SMALL CLAMS 45 though it assumes various shapes.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmollusks, bookyear190
