LUCINA. 179 



The pure whiteness, symmetrical form and regular 

 markings make this a very pleasing shell. 



Lucina Nuttalli, Conr., Nut-tal'-li. The shell of 

 this species is similar in shape to that of the last, but 

 is more highly sculptured. The sharp, fine lines of 

 growth are crossed by many delicate rays, making 

 its surface look like fine basket-work. It is some- 

 what flattened and ridged along the hinge-line. 

 Color white, length an inch or less; southern. 



Diplodonta orbella, Gld., Di-plo-don'-ta or-bel'-la. 

 The shell of this pretty species resembles Lucina 

 Californica in size, color and surface, but the valves 

 are greatly inflated; so much so that small specimens 

 are nearly spherical, and resemble white marbles. It 

 has a wide range from north to south. 



Now for a neat little shell, not half an inch long, 

 which may often be found in the sand, but live speci- 

 mens of which may occasionally be discovered, 

 fastened to the rocks in concealed places. A rather 

 large picture of it is given in Fig. 152, and its large 

 name is Lctzaria subquadrata, Cpr., Iya-za'-ri-a sub- 

 quad-ra'-ta. It is strong, full, and marked with 

 fifteen rounded ribs, which seem to radiate 

 Jjli^ from one corner of the nearly rectangular 

 shell. Ivimule cordate and conspicuous; liga- 

 Fig- 152. ment external, at the base of a broad depres- 

 sion. Cardinal teeth strong, three in number; pallial 

 line entire; color brownish white, sometimes deeply 

 stained inside with, purple; edge slightly crenulated. 



Crassatella marginata, Cpr., Cras-sa-tel r -la mar- 

 gin-a'-ta. Shells minute, about the size of large pin- 

 heads; somewhat triangular; yellowish, marked with 

 chevrons of brown. 



