170 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
anterior and posterior ends above and widely separated below. 
The ligamental area is longitudinally folded. A membrane 
unites the shells anteriorly to the beaks, and terminates within a 
short distance of the anterior edge of the shell, diagonally 
wrinkled for a short space and then longitudinally wrinkled. 
Where this membrane ends, the pedal opening begins as shown 
in the figure. 
CRYPTODON sp. 
Fig. 25. Length, 10 mm. 
The foot of this creature is long, narrow, and cylindrical. 
It resembles a long intestinal worm. Its usual appearance is first 
a cylindrical enlargement transversely stri- 
ated, then an abrupt contraction to one third 
of its diameter, and then an enlarged club- 
shaped extremity. It varies in its enlarge- 
ments and may be twice as long as shown in 
the figure. At intervals it appears as a long 
cylindrical rod with no dilatations or con- 
tractions. The mantle is open and there 
Fig. 2b.—cryptodon sp. g^j.g ^^ sigus of syphoual tubcs indicated by 
papillae or other features. Within, lobular enlargements spring 
from the sides of the body filled with eggs as described by others. 
TURTONIA MINUTA (Fabricius). 
Fig. 26. Length, 2 mm. 
Despite the diminutive size, the shell is quite hard and rigid. 
In life there was no resemblance whatever to the figure given of 
the species in Forbes and Hanley. There is no trace of a syphon 
as figured by these authors. The mantle is open throughout. 
The syphonal opening is represented by a loop-like fold with 
edge sUghtly undulating. Three figures are given showing its 
appearance at times. The lower part of the syphonal opening 
is distinctly scalloped, the foot is long and slender; edge of the 
mantle is double. On the anterior ventral margin of the mantle 
is an extensive thickening that seems like a pouch. On the 
outside of the shell, a large area corresponding to the mantle 
thickening is much lighter in color and shows distinctly. Near 
the beak I counted fourteen eggs in one specimen and seven in 
another. This was on June 18. The gill has a chitinous frame- 
