UNIVALVE MOLLUSKS 129 



ter. The color is light brown with more or less 

 darker rays, and its length is one-fourth of an inch 

 or a little more. The interior muscle-scar is divided 

 on one side by a siphonal groove, but this mark is 

 not always very distinct. This little mollusk lives 

 on rocks between tides, and is not found very often. 

 When disturbed it gives out a milky fluid. 



Gadinia reticulata^ Sby., the Netted 

 Button-shell. A rather small specimen 

 of this pretty shell is shown in Figure 

 98. It is usually low arched, though it 

 varies considerably in this respect. There ^ig. 98 

 is a nearly central apex, from which run radial lines 

 to the edge of the shell. These rays are crossed by 

 defep, circular lines of growth, giving the shell a 

 netted or reticulated appearance. The color is pure 

 white and the shell is quite solid. I have found a 

 few specimens living on mussel-bearing ledges, near 

 the low water line, but it is not often found alive, 

 except occasionally in a tide grotto. Dead shells 

 are frequently washed up from the sea by the waves. 

 The peculiar markings make them easy to identify. 

 Sometimes live shells are found, greenish white in 

 color, quite conical, and nearly smooth. 



