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University of California Publications in Zoology | Vou. 14 
Pholadidea Goodall 
Pholadidea ovoidea (Gould) 
Plate 30, figures la, 1b, 2a, and 2b 
Pholas (Parapholas) ovoidea Gould (1851), p. 87. 
Description—Professor H. A. Clark has kindly assisted the writer in trans- 
lating the original description: 
Shell oval, somewhat solid, ashy colored, posterior end gaping widely and 
with a much produced epidermis; anterior ventral margin closed by a caleareous 
plate; beaks situated near the anterior third of the shell; valves divided by a 
median groove, anterior portion rounded, with concentric, radially striated 
layers, with a subcylindrical, roughened posterior portion, marked with distinet 
striae; cardinal region tapering, dilated toward the apex; with no auxiliary 
valves. 
Length, 20 to 35 mm. 
Occurrence.—At stations D 5808 (7), D 5846 (1, 4). 
Living specimens of this species were dredged by the Survey at a 
depth of 50 fathoms, within the Golden Gate. 
Range.—Bering Sea to Gulf of California (Dall). 
Pholadidea penita (Conrad) 
Plate 30, figures 3a and 3b 
Pholas penita Conrad (1837), p. 237, pl. 18, fig. 7. 
Parapholas penita, Carpenter (1856a), p. 210. 
Pholadidea penita, Wood and Raymond (1891), p. 55; Arnold, R. (1903), 
p. 184. 
Description.—This species was originally described by Conrad (1837) as 
follows: 
“‘Shell ovate, elongated, contracted submedially and grooved; anterior side 
inflated, with decussating lines, the radiating striae having a granulated appear- 
ance, posterior side subcuneiform, extremity truncated, with a membranous 
expansion or appendage; apophysis oblique, slender, spoon-shaped at the ex- 
tremity.’’ 
Length, 15 to 70 mm. 
Occurrence.—At stations D 5709 (1), D5808 (1), D5845 (3), 
D 5846 (5), Richmond* (9), Sausalito (7), Presidio (f.). Borings 
were found in rocks at D 5702 (2), D 5742, D 5801, D 5809. 
This boring mollusk was taken by the Survey at seven stations 
within San Francisco Bay at depths ranging up to 50 fathoms. A 
living specimen was dredged from 43 fathoms. 
Range.—Chirikoff Islands, Alaska to San Pedro, California (Dall). 
