14 



University of Michigan 



partially suppressed and in old shells both become jagged, and 

 usually one well-developed, slightly curved, long lateral, with 

 sometimes an indication of another more dorsad; beak cavi- 

 ties rather shallow, showing or just obscuring the dorsal scars ; 

 anterior muscle scars deep and sculptured by anastamosing 

 lamellae ; posterior scars well impressed only at the anterior 

 end; nacre white to salmon or lavender, without distinct, cop- 

 pery tinge ; radially striate and iridescent in the younger shells, 

 but thickened and minutely pebbled anteriad in the older 

 specimens. 



Variation in E. liebmanni cuatotolapamensis, n. subsp. 



This is a smaller form than typical liebmanni, with, appar- 

 ently, a stronger tendency towards ornamentation. Simpson 

 (1914) omits any mention of the ornamentation in his descrip- 

 tion of B. liebmanni, but Philippi (1849) says: "The beaks 

 of my examples are very widely and strongly eroded ; how- 



