284 Umversity of Cahfornia Publications in Zoology  [Vou.14 
Occurrence.—At stations D 5714 (4, 9), D5716 (39), D 5717 (2, 
25), D 5718 (5), D5719* (f.), D 5721 (25, 1), D 5722 (4, 4), D 5723 
(4), D 5724 (9), D 5725 (1), D 5726 (5), D 5729 (20, 21), D 5730 (5), 
D 5747 (2), D5749 (175), D 5750 (8, 18), D 5751 (17, 14), D 5754 
(32), D5757 (4, 20), D5758 (200, 7), D 5864 (3, 9), D 5766 (11, 
11), D 5767 (9, 56), D 5768 (f.), D 5771 (8, 3), D 5772 (1), D 5780 
(81, 42), D 5781 (2), D 5782 (2), D 5784 (5), D 5787 (11), D 5793 (8, 
6), D5795 (17), D 5810 (35), D 5815 (1, 20), D5815 A (5), D 5816 
(15), D 5816 B (3), D 5817 (2, 2), D5817 A (96, 118), D 5817 B (4, 
15), D 5818 B (20, 9), D 5819 (48), D 5819 A (f.), D 5819 B (3, 4), 
D 5820 (5), D 5820 A (1), D 5822 A (187), D 5823 (4, 1), D 5823 B 
(2), D 5824 A (f£.), D 5824 B (1), D 5825 A (1), D 5831 (1), D 5832 A 
(1), D 5833 (1), D 5834 (2), D 5841 (21), D 5847 (1), D 5847 B (4), 
MeNeer’s Landing (7, 29), Red Rock (1), Key Route Pier, Oakland 
(8), Sausalito (2, 7), Bonita Point (1), and questionably at D 5720, 
D 5727, D 5752 and D 5756. 
This species was first noted by Newcomb in 1874 and named by 
him M. hemphill. It has since been recognized as being the eastern 
species, and is presumed to have been inadvertently introduced. At 
present this edible clam has a rather wide distribution on the West 
Coast, occurring abundantly within San Francisco Bay and in other 
bays northward to Puget Sound. By some authors it is considered to 
have a circumpolar range extending southward into Alaskan waters. 
As yet it has not been reported from the Californian Pleistocene beds 
nor from the undisturbed kitchen middens of the San Francisco region. 
This bivalve has a general distribution within the bay, which is per- 
haps not correctly represented in plate 52 since it is a littoral or adlit- 
toral species, which burrows deeply in mud or sand. 
Range.—Victoria, B. C., to Monterey, California. Introduced from 
the Atlantic (Dall). 
Mya (Cryptomya) californica (Conrad) 
Plate 31, figures 2a and 2b, plate 53 
Sphaenia californica Conrad (1837), p. 234, pl. 17, fig. 11. 
Cryptomya californica, Carpenter (1863), p. 637; Wood and Raymond 
(1891), p. 55; Arnold, R. (1903), p. 180. 
Description—This species was originally described by Conrad (1837) as 
follows: 
‘«Shell suboval, convex-depressed, with radiating striae; obscure, except 
towards the posterior extremity, where they are distinct; posterior margin 
