GUNDLACHIA. 233 
Genus GUNDLACHIA, Pfeifer. 
1. GUNDLACHIA CALIFORNICA, Rowell. 
Plate 2, figs. 19—21. 
Shell with the aperture suboval, obliquely 
expanded towards the left, posteriorly rounded 
and wider anteriorly. Internal shelf reach- 
ing forward about one-fifth the length of the 
shell, its margin slightly concave and oblique. 
Dorsal surface convex, becoming somewhat 
keel-shaped towards the apex, which is 
strongly and obliquely deflected so as to make 
the right border nearly a straight line, while 
the expansion on the left projects nearly as 
far back as the apex at an obtuse angle. 
Structure corneous, with strong concentric 
lines of growth and faint radiating strie. 
Color dark brown, opaque; inner surface 
(27) 
