. Beginners' Zoology . Why. Does it thrust the foot forward and pull up to it,or thrust the foot back and push. (Mussels and clamshave no bones.) Does it go with the blunt end or the moretapering end of the shell forward. (Fig. i88.) Can amussel swim . Why, or why not ? 97 98 BEGINNERS ZOOLOGY. Fig. i88. -Anodon, or fresh-watermussel. shells for valves in pumps. Lay the shells, fitted together, in your hand with t/te kin^tside away from you and the blunt end to the lcft{¥\g. i88). Is the right or the left shelluppermost. Which is thetop, or dorsal, side .-* Whichis the front, or anterior,end ?
. Beginners' Zoology . Why. Does it thrust the foot forward and pull up to it,or thrust the foot back and push. (Mussels and clamshave no bones.) Does it go with the blunt end or the moretapering end of the shell forward. (Fig. i88.) Can amussel swim . Why, or why not ? 97 98 BEGINNERS ZOOLOGY. Fig. i88. -Anodon, or fresh-watermussel. shells for valves in pumps. Lay the shells, fitted together, in your hand with t/te kin^tside away from you and the blunt end to the lcft{¥\g. i88). Is the right or the left shelluppermost. Which is thetop, or dorsal, side .-* Whichis the front, or anterior,end ? Is the straight edgeat the top or at the bottom ?Our word valve is derivedfrom a word meaning shell,because the Romans usedIs the mussel a univalve or abivalve .* Which kind is the oyster} The Does the mussel have bilateral symrnetry ? Can youfind a horny covering, or epidermis, over the limy shellof a fresh specimen} Why is it necessary } Does waterdissolve Hme .? Horn . Find a bare spot. Does any ofthe shell appear to be missing there } The bare projection on each shell is called the the umbo near the ventral or the dorsal line} Theposterior or anterior end} Isthe surface of the umbonesworn ? Do the umbones rubagainst the sand as the musselploughs its way along? How
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