Fig. 77. Changes in form of shell. A series of drawings illustrating the 

 changes from the early veliger (the first shell), which is Vio of a millimeter in size, 

 to a 2-millimeter scallop. Note (a) change from flat-hinged veliger (1) to the pro- 

 dissoconch (2), with prominent umbones; (6) return to a straight hinge (3), width 

 greater than height; (c) width and height become equal (8); (d) formation of 

 "ears" (10). 



