MORSE: OBSERVATIONS ON LAMELLIBRANCHS. 
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The foot is long and narrow with a deep groove running the 
whole length of the ventral surface, yellowish white in color. 
When the shell is placed on its back the creature struggles with 
its foot widely extended and finally reaching down to the bottom 
of the dish secures a hold and instantly turns the shell over and 
crawls away by jerks, reaching out its foot and pulling itself 
along. The mantle is entirely open and extends beyond the edge 
of the shell; its border is marked by ocular dots at the ends of 
the spaces between the ribs (Fig. 7, a). 
ARCA TRANSVERSA Say. 
Fig. 8. Length, 35 mm. 
The mantle expands beyond the edge of the shell ; ocular dots 
were not observed but rich, dark brown scallops appear at the 
end of each rib. The edge of the mantle is thrown into delicate 
folds, j'-ellowish in color. The foot appears in two folds as shown 
in figure. It is light reddish liver-color. 
In the young shell a millimeter in length, Fig. 8, a, the oblong 
Fig. 8. — Area transversa Say. 
circular protoconch, somewhat tumid, is seen. It is corneous 
and polished. The young shell at this stage is translucent, 
flecked with white spots except in the central furrow running 
from the beak to the ventral edge of the shell. In front of the 
beak, two teeth show and behind the beak three teeth have 
already formed. In examining a young Area from Manila, the 
same deep depression running from the beak is seen. This 
