76 SLIPPER-SHELLS. 



that of the next species, Crepidiila rttgosa, Nutt., 

 ru-go^-sa. The surface is somewhat roughened and 

 shaggy, and the apex is on the very edge of the shell. 

 The color of the outside is light brown, sometimes 

 marked with narrow stripes, while the inside is dark 

 brown, except the deck, which is white. The length 

 is sometimes more than an inch. 



Crepidula navicelloides^ Nutt , nav-i-sel-loi'-des, is 

 the White Slipper-shell, and is shown in 

 Fig. 6i. This species has a pure white 

 shell, and 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 mollusk makes his 

 Fig. 6i. home upon the rock, and the back of his 

 shell becomes rough and discolored; again, live spec- 

 imens may be found within the aperture of a dead 

 spiral shell, and then the Crepidula is smooth, curved, 

 elongated, and almost transparent. The common 

 length is less than an inch. 



A small species of this extensive genus is named 

 Crepidicla dorsata^ Brod. , dor-sa^-ta; It is nearly 

 circular in outline, with a small, curv^ed, partly 

 detached deck, and a more or less wrinkled shell, 

 about half an inch in diameter. The color is brown 

 and white, sometimes mottled, and the shell is thin 

 and flat. 



Crepidula aculeata^ Gm., a-ku-le-a'-ta, is a small 

 southern species, with a low apex, curved to one side. 

 The yellowish white shell is marked by many irregu- 

 ular, radiatng ridges. It occurs ^'around the world." 

 (Cpr.) 



