298 University of California Publications in Zoology — [Vou. 14 
outside near the slits. Sutural plates broad, the sinus extremely shallow and 
small. 
“Girdle rather narrow, densely covered with round, curved or curled hairs. 
Gill row as long as the foot.’’ 
Length, 5 to 50 mm. 
Occurrence.—At stations D 5773 (3), D5774 (1), D5845 (1), 
Presidio* (72), Sausalito (7), Bonita Point (3). 
This species is represented in the Survey collections by several 
specimens that were taken within and along the shores of the middle 
division of the bay. They were dredged only at stations where the 
bottom was stony. A single living specimen was obtained in the outer 
portion of the Golden Gate at a depth of 33 fathoms. 
Range.—Shumagin Island to San Diego, California. 
Mopalia wosnessenski Middendorff 
Mopalia wosnessenskii Middendorff (1847-1849), p. 119; Carpenter (1863), 
p- 648; Wood and Raymond (1891), p. 55. 
Mopalia ciliata (Sowerby) var. wosnessenskii Pilsbry (1892-1893), p. 305, 
pl. 64, figs. 69-73. 
Description.—Pilsbry (1892) described this species as follows: 
‘‘Shell elongated, the back roundly arched, not carinated; dull colored, 
varying from light olive or green to drab, generally with blackish patches on 
each side of the middle, and more or less mottled throughout with dusky. Seulp- 
ture much fainter than in typical ciliata. Girdle apparently lacking the white 
spicules described above.’’ 
Occurrence—One valve was obtained from station D 5808*. 
The single valve representing this species in the collection of the 
Survey was dredged from a rocky botton at a depth of 43 fathoms. 
Range—Sitka, Alaska, to San Francisco, California. 
Placiphorella Carpenter 
Placiphorella sinuata (Carpenter) 
Mopalia sinuata Carpenter, Pilsbry (1892-1893), p. 303, pl. 62, figs. 95, 
96, 97. 
Placiphorella sinuata, Oreutt (1915), p. 73. 
Description.—This chiton was deseribed by Pilsbry as follows: 
“Shell oblong, elevated and strongly ecarinated, the side-slopes straight. 
Color whitish, clouded with delicate blue-green and maculated with rich tawny 
brown. 
““Median valves hardly beaked, the lateral areas not raised, but strongly 
defined by an elevated diagonal rib; sculptured with two oblique series of fine 
riblets forming a lattice pattern. Central areas having a series of longitudinal 
