1918] Packard: Molluscan Fauna from San Francisco Bay 261 
ANATINACEA 
PANDORIDAE 
Pandora Bruguiére 
Pandora filosa (Carpenter) 
Plate 19, figures 2a and 2b 
Kennerlia filosa Carpenter (1863), p. 638; (1864c), p. 602. 
Pandora (Kennerlia) filosa, Carpenter (1865a), p. 55; Arnold, R. (1903), 
p. 124, pl. 18, fig. 3. 
Description.—This species was described by Arnold (1903) as follows: 
“*Shell small, planoconvex, elongate-oval, thin; umbones minute, about one- 
fourth length from anterior extremity; anterior and posterior dorsal margins 
straight, making an angle of 160 degrees at the umbo; ventral margin arcuate; 
posterior extremity long, narrowed and truncated at the end; anterior rounded 
up from base but making an angle with dorsal margin; a single prominent 
posterior, submarginal ridge runs from umbo to extremity on each valve, being 
nearer the margin in the flat valve; surface of both valves sculptured by numer- 
ous fine, concentric, incremental lines, and that of the right valve by fine 
radiating sulcations; left valve with a thin hinge ossicle; right valve with two 
ossicles, the anterior one being short.’’ 
Length, 10 to 18 mm. 
Occurrence.—At stations D 5785 (13), D 5786 (8, 1), D 5787 (1), 
D 5788* (3), D5789 (3, 3), and west of the Farallon Islands (7). 
This species is restricted to the waters outside the Golden Gate. 
Living specimens were dredged in the vicinity of the Farallon Islands, 
being the most abundant at station D 5785. Dredged in depths rang- 
ing from 39 to 68 fathoms, and at one locality west of the Farallon 
Islands in 815 fathoms. 
Range.—Nunivak Island, Alaska, to Point Abreojos, Lower Cali- 
fornia (Dall). 
LYONSIIDAE 
Lyonsia Turton 
Lyonsia californica Conrad 
Plate 18, figure 3 
Lyonsia californica Conrad (1837), p. 248, pl. 19, fig. 21; Carpenter (1863), 
p- 638; Wood and Raymond (1891), p. 55; Arnold, R. (1903), p. 125. 
Description.—Conrad’s (1837) original description is as follows: 
““Shell produced, equivalve; posterior side narrowed, truncated at the 
extremity; umbo inflated; epidermis with radiating striae. Length, one and a 
half inches.’’ 
Length, 19 to 22 mm. 
