CHIONE. 



187 



The color is brownish white, deeply stained inside 

 with pnrple; length two inches or less. 



Chioiie siiccmcia, Val., suk-sink'-ta, is a similar 

 species. In Fig. 159 we have a 

 view of the distinct, cordate luniile 

 which is so conspicuous a mark of 

 this shell. 



In general form and size it res- 

 embles the last species, but is 

 marked by less frequent concentric 

 ridges. The shell is white, strong, 

 and heavy. 



CJiiojie fiitctifraga^ Sby., fluc- 



tif-ra-ga. Shell very strong and 



Fig- 159- heavy, valves nearly circular when 



young, and sculptured into a network. When older, 



the shell becomes somewhat triangular and the latter 



part is prolonged. 



There is no distinct lunule as in the other species; 

 the ribs and lines are rounded, and the edges are 

 marked with fine crenulations. Externally the shell 

 is ding)', but it is pure white within, with purple 

 spots at or near the muscle scars. The shell is an 

 inch or two in length; southern. 



Fig. 160 represents one of the most graceful of our 

 bivalve shells. Its name is Amiantis callosa^ Conr., 

 Am-i-an^-tis cal-lo'-sa. It is a pure white shell, full 

 in the center and quite thin at the edges. Its sculp- 

 turing consists of many rounded, concentric lines, 

 equal in size to the intervening grooves. There are 

 no radial markings whatever. The lunule is small, 

 set beneath the prominent umbones. 



The ligament is external, the pallial sinus moder- 

 ate, while the hinge has complicated cardinal teeth 



