32 CALIFORNIA SEA-SHELLS. 



and concentric grooves. The low whorls are 

 marked by spiral, raised lines, broken into 

 numerous points, which give the shell a character- 

 istic appearance; rounded teeth also line the 

 lower part of the aperture. Its color varies 

 from li^ht to dark brown. 



Three fine species of Top-shells, which always 

 delight the heart-of one who loves to study and 

 collect these graceful forms of nature, have the 

 common name Calliostoma. They are shown in 

 Figs. 2, 3, and 4, PI. Till. They commonly 

 live outside the low water mark, upon the kelp, 

 where the rocks can not injure their delicate shells. 



At times, they are very difficult to obtain, prob- 

 ably sinking to the bottom ; but it is said that 

 when the sun shines brightly they crawl up near 

 the surface, and can easily be captured by the 

 aid of a boat. 



CcilUostoma costatum, Mart., Fig. 2, PI. Till, 

 is quite thick and strong. It has four whorls 

 rounded and marked with fine spiral ridges. 

 The thin, reddish brown, outer coat is easily 

 peeled off, showing the bright, pearly blue shell 

 underneath. The aperture of dead shells is often 

 inhabited by the White Slipper-shell, Crepidulo 

 navicelloides. 



Fig. 3, PI. Till, is a fine picture of Calliosto- 

 ma annulatum, Mart., Banded Top-shell, It is 

 a very pretty shell, thin and delicate, sharply 

 conical, marked by fine spiral lines, which are 

 cut into minute grains. Color, light brown, with 

 darker dots, and a spiral line of violet. The 

 aperture is nearly square, and the short columel- 

 la is pearly. 



