SHELLS WITHOUT CANALS 207 



spines. The cup is small, white and triangular. This 

 species assumes many forms, and is sometimes almost 

 white and free from spines. It has been found as far 

 north as Monterey, but its home is along the southern 

 coast. 



Calyptrcza inamillaris^ Brod., the Chinese Hat, 

 has a white shell, of a low conical shape, running up 

 to a point, while inside there is a twisted deck, thin 

 and sharp, reaching nearly to the margin. Sometimes 

 this shell has a diameter of an inch or more, though 

 usually it is considerably smaller. It is said to ex- 

 tend from Puget Sound to Central America, but it 

 is not a common shell on our coasts. It was dredged 

 by Lowe and Roper off San Pedro. This species is 

 also known by the name Galerus mamillaris. 



There is a large group of mollusks whose shells are 

 somewhat turtle-shaped, with a floor built over a 

 part of the lower surface. When turned over they 

 somewhat resemble a Chinese slipper, with a place 

 for the toes of the wearer's toot. So apparent is the 

 resemblance that they are universally called Slipper- 

 shells. 



Crepidula adunca^ Sby., the 

 Hooked Slipper-shell, Figure 201, is 

 perhaps the commonest species. The 

 apex is strongly recurved, suggesting Fig. 201 

 the name, and the surface is brown, 

 though the internal deck is white. Living speci- 

 mens may often be found growing upon other shells, 

 and sometimes they are found piled one upon another 

 three deep. Young shells often have the apical hook 

 quite pointed. Living specimens are often found 



