Bull. U. S. F. C. 1897. 
(To face page 402.) 
Plate IV. 
B c D 
SALMON-COLORED PEARL, WEIGHING Hi- PEARL GRAINS, LYING LOOSE WHERE IT WAS FORMED IN A SHELL. 
FROM LINN JUNCTION, IOWA. 
The pearl is nearly hemispherical, or " button-shaped," somewhat one-sided, but perfect above. It occupied a depression at the posterior end of the 
right valve, and had caused a marked outgrowth or protuberance of the other valve. 
A. Interior view of the right valve, with the pearl in place. 
B. The same valve with the pearl removed, showing the depression where it had lain. 
C. The pearl itself taken out. 
D. Exterior view of the left valve, showing the protuberance corresponding to the pearl. 
