1918] Packard: Molluscan Fauna from San Francisco Bay 297 
Mopalia ciliata (Sowerby) var. lignosa (Gould) 
Chiton lignosus Gould (1846a), p. 142. 
Mopalia vespertina Gould, Carpenter (1863), p. 648. 
Mopalia lignosa, Pilsbry (1892-1893), p. 299, pl. 63, figs. 58, 59. 
Mopalia ciliata var. lignosa, Wood and Raymond (1891), p. 58. 
Description.—Pilsbry (1892) described this form as follows: 
“*Shell oval, elevated, carinated or angular at the dorsal ridge, the side- 
slopes straight. Surface lusterless, apparently smooth; grayish, greenish or 
bluish with radiating streaks, lines and flammules of brown or purple-brown. 
Under a lens the lateral areas appear nearly smooth; the central areas being 
closely and finely pitted all over. Girdle narrow, sparsely hairy. 
Interior white and light blue.’’ 
This form has been lsted from this region by Wood and Raymond. 
It was not taken by the Survey. 
Range.—Vancouver Island to Monterey, California (Pilsbry). 
Mopalia kennerleyi Carpenter var. swani Carpenter 
Mopalia kennerleyi var. swani Carpenter (1864b), p. 426. 
Mopalia wosnessenskii Middendorff€ var. swani, Wood (1891), p. 94. 
This form reported from this region by Wood appears to be but a 
doubtful variety of M. kennerleyt. 
Range.—Typieal species ranges from Unalaska to Monterey, Cali- 
fornia. 
Mopalia muscosa (Gould) 
Chiton muscosus Gould (1846a), p. 145. 
Mopalia muscosa, Carpenter (1863), p. 648; Pilsbry (1892-1893), p. 295, 
pl. 63, figs. 46-48. 
Description—tThis species was described by Pilsbry (1892) as follows: 
“*Shell oval, elevated or depressed, the dorsal ridge more or less angular. 
Valves strong. Surface lusterless, finely sculptured with wavy, crenulated 
longitudinal riblets, often more or less obsolete. Color generally dull brown, 
blackish-olive or grayish, but sometimes bright orange, scarlet or vivid green. 
‘*Median valves hardly beaked, the lateral areas slightly raised, granose, 
limited by a raised granose riblet. Central areas having close fine longitudinal 
riblets, with ecrenulated or latticed interstices, the riblets finer and converging 
on the ridge of the last 6 valves, diverging on the second valve, or strongly 
diverging on the ridge of all valves, like a series of superimposed Vs. Anterior 
valves having about 10 narrow radiating granose riblets, the intervals granose. 
Tail valve depressed with posterior mucro, the posterior slope very short, emarg- 
inate behind. 
“Interior bluish-green, stained with lilac on the central callus. Anterior 
valve having 8, median 1 short slit, the teeth long, deeply striated outside and 
thickened or propped outside at the sides of the slits. Posterior valve having 
a rounded sinus behind, with one oblique slit on each side, the plate roughened 
