SELES WilthoOur CANALS 
cus) 
vo 
on 
brown, while the deck is as white as the purest 
marble. 
Crepidula navicelloides, Nutt., the 
White Slpper-shell, Figure 245, may 
easily be recognized by its color, its 
flattened shape, and by the very thin 
and delicate deck, which is shown in 
the engraving. Sometimes this mol- 
Pigs 245 lusk makes its home upon the rock, 
and the back of his shell becomes rough and dis- 
colored; while again live specimens may be found 
within the aperture of a dead spiral-shell, and then 
the slipper is smooth, curved, elongated, and 
almost transparent. 
Crepidula lessoni, Brod., Lesson’s Slipper-shell, 
resembles a long, narrow specimen of the last 
species. The shell, however, is thickened by a 
number of layers, partly detached at their edges. 
The color is white. There is also a short and 
heavy variety known as var. explanata, Gld., which 
some consider as a distinct species. 
A small species of this extensive genus is named 
Crepidula dorsata, Brod., the Wrinkled Slipper- 
shell. It is nearly circular, thin and flat, with a 
small, eurved, and partly detached deck. The 
wrinkled brown and white shell is about half an 
inch across. 
Crepidula aculeata, Gmel., the Prickly Slipper- 
shell, is a small southern form. The yellowish- 
white shell has a low apex, eurved to one side, and 
is diversified by many irregular radiating ribs. 
Capulus californicus, Dall, the California Cap- 
shell, is a new and fine species, specimens of which 
