864 THE AMERICAN .NATURALIST. [Vor. XXXIV. 
ears are unnotched.! Since the byssus passes out on the right 
side, the right side of the young Pecten lies next the sub- 
stratum, while the left side is broadly exposed to the water 
above. I was interested to see whether the Pecten ever lies on 
its left side —a condition which would be comparable in a way 
Fic. 1. Ey Photographs of Pecten irradians from Cold Spring Harbor : a, 4, two cases of partial 
division of a rib; c, case of interpolation of a secondary ridge between two primary ones; 
e, f, showing an extremely small (14) and extremely large (20) number of rays. 
with left-handedness in dextral gastropods. If the abnormal 
condition ever occurs, it will show itself by the circumstance 
that the notch will appear on the left side of the valve, viewed 
exteriorli. Now, although over a thousand notched shells 
1 Fig. 1, bottom, left. 
