1918 | Packard: Molluscan Fauna from San Francisco Bay 323 
Occurrence.—At stations D 5768 (8, 10), D 5781 (5, 3), D5782* 
(6, 12), D 5788 (1, 2), D 5784 (1, 4), D5810 (67), D 5811 (1, 12), 
D 5847 (1). 
This species has been introduced inadvertently along with the seed 
oysters from the Atlantic. The large number of living specimens 
obtained at or in the vicinity of the oyster beds at the southern end 
of San Francisco Bay indicates that this exotic species has gained an 
assured foothold within these local waters. It was first recognized 
on this coast by Stearns (1899a) under the name of C. convera var. 
glanca Say. 
It has been dredged by the Survey in the southern portion of the 
bay, in the vicinity of the oyster beds, and at one locality off the Ala- 
meda shore. Living specimens were obtained on gravel or shell bottoms 
in depths ranging from 1 to 4 fathoms. It commonly occurs attached 
to a living oyster. 
This form differs from the West Coast species Crepidula adunca 
in having a higher apex which is more centrally located than in the 
western form. 
Range.—San Francisco, California, Nova Scotia to Florida. 
Crepidula nivea Adams 
Plate 35, figures 7a and 7b, plate 55 
Crepidula nivea Adams, C. B. (1852), p. 234; Keep (1911), p. 208. 
Crepidula navicelloides Nuttall, Carpenter (1863), p. 654. 
Description.—This species was originally described as follows: 
“*Shell ovate-elliptic; rather thick; within snow white; without dingy 
white, sometimes with a faint tinge of brown; very irregularly concentrically 
more or less wrinkled, with very distinct striae of growth; apex turned more or 
less to the right, moderately prominent, marginal; septum longitudinally sub- 
angular, with a deep sinus at the left and a shallow one at the right; margin 
thick, exhibiting striae of growth... .’’ 
Length, 3 to 25 mm. 
Occurrence-—At stations D 5708 (1), 5712 (1), D5723 (7, 1), 
D 5744 (1), D5756 (1), D5764 (3), D5766 (4), D5767 (53, 11), 
D 5868 (67, 3), D5781 (32), D 5782* (7, 3), D 5783 (1), D5784 (1, 
105), D 5810 (8, 2), D 5811 (1), D 5813 (1, 1), D5817 (3), D5817 B 
(1) D 5846 (6), Standard Oil Pier, Richmond (6), Red Rock (2), 
and questionably at D 5737, D 5833. 
This mollusk has been reported from the Farallon Islands and San 
Francisco Bay. Living specimens were obtained by the Survey at 17 
stations quite generally distributed from the lower extremity of the 
