264 University of California Publications in Zoology [Vou-14 
Occurrence.—At station D 5789 (6). 
Several valves were obtained at a single station near the Farallones 
in 46 fathoms on a bottom of dark green sand. According to Dall, 
this species ranges in depth from 8 to 135 fathoms. 
Range.—Alaska to Coronado Island, California (Dall). 
Phacoides tenuisculptus (Carpenter) 
Plate, 19, figures la and 1b 
Lucina tenuisculpta Carpenter (1863), p. 642; (1865a), p. 57; Arnold, R. 
(1903), p. 133. 
Phacoides tenuisculptus, Dall (1901b), p. 828, pl. 40, fig. 5. 
Description.—Arnold (1903) describes this species as follows: 
‘Shell small, orbicular, deeply convex, thin; umbones prominent, central; 
surface sculptured by ‘numerous fine, concentric lines and radiating striae; 
lunule prominent, the greater part being in the right valve; cardinal teeth 
small, laterals prominent; anterior muscle-impressions not as elongated as in 
L. acutilineata and others.’’ 
Length, 2 to 5 mm. 
Occurrence—At stations D5785 (3, 2), D5786* (31), D5787 
(4), D 5788 (3, 1), D 5789 (2, 3), D 5830 A (4), and questionably at 
D 5744, D 5825 A, D 5826 B, D 5828 B. 
Living specimens are restricted to the collections from the open 
ocean, occurring abundantly at station D 5786 at a depth of 40 fath- 
oms. Several shells were obtained in the middle portion of the bay 
that have been questionably referred to this species. This species 
lives.on a fine-grained sand. 
Range——Bering Sea, Alaska, to Coronado Island, California 
(Dall). 
THYASIRIDAE 
Thyasira Leach 
Thyasira gouldi (Philippi) 
Plate 20, figure 5 
Axinus Thyasira gouldi Philippi (1845-1846), p. 75. 
Cryptodon flecuosus Carpenter (1863), p. 643. 
Thyasra gouldi, Arnold, R. (1903), p. 135. 
Description.—Arnold (1903) described this species as follows: 
‘‘Shell small, globular, posterior side augulated or furrowed; umbones much 
recurved; surface sculptured with fine incremental lines; lumule indistinct, 
depressed in front of beaks; ligament external, placed in a groove on the hinge- 
line and outside the hinge-plate; teeth wanting. 
Length, 7 mm. 
