CLASS PELECYPODA 
213 
Pholadidea parva Tryon, 1865. 
Plate 22, figs. 11, 12. 
Amer. Jour. Conch., 1:39; pi. 2, figs. 4, 5. 
Shell small, ovate, inflated, rather thick. Surface divided by an 
oblique impressed rib, posteriorly to which it is concentrically striate while 
anteriorly it is radiately ribbed. The flexed dorsal margins are each 
covered with a thick, irregularly shaped accessory valve, with a single 
central valve posterior to them. The latter is somewhat pentagonal, 
emarginate in front. Hiatus filled by a heavy callus, which juts out 
somewhat into a point or beak, instead of preserving a rounded outline. 
Length, 0.33; height, 0.50; diameter, 0.30 of an inch. (Tryon.) 
Type in Try on’s Cabinet. Type locality, Lower California, in Haliotis. 
Range. San Pedro, California, to Lower California. 
Subgenus Nettastomella Carpenter. 
Pholadidea rostrata Valenciennes, 1846. 
Plate 13, figs. 10, 11, and plate 38, figs. 7, 10. 
Voyage of Venus, Atlas, pi. 24, figs. 4, 4a. Marine shells of Puget Sound, p. 66. 1924. 
Shell small, short, widely gaping anteriorly, sculpture radiately sca¬ 
brous, divided by a constricted deep groove; behind the groove concentri¬ 
cally ridged; anterior portion with fine concentric ridges which continue 
around the aperture, curved up to the umbos, thus forming an inverted 
U-shaped opening. The valves at the posterior end are prolonged like a 
duck’s bill. It differs from Jouanettia in having the valves equal, and 
from Pholadidea s.s. in that the ends are shelly and prolonged, instead of 
a cornaceous cup. A very delicate thin shell, of a pure white color. 
Found living in the shale with other species of Pholads. Valenciennes 
figured and named the shell but did not publish a description. Length of 
adult specimen figured about 28 mm. (Oldroyd.) 
I have given Valenciennes’ figure of his type on plate 13, figs. 10, 11. 
This has been wrongly called P. darnhni, a South American species. 
P. darwini is figured on plate 42, figs. 7, 8. 
Type locality and location of the type not known to the present writer. 
Range. Vancouver Island, British Columbia, to San Diego, California. 
Genus MARTESIA (Leach) Blainville, 1824. 
Valve lengthened behind when full-grown, by a plain border; umbonal 
valves one or two, dorsal and ventral margins often with narrow, accessory 
valves; surface impressed with one or more furrows. M. striata burrows 
in hard timber; M . ierediniformis was found in cakes of floating wax on 
the coast of Cuba; M. australis in (fossil ?) resin, on the coast of Australia; 
