CHITONS. 41 
are most Yik< ly to be met with by those who 
read this little book. 
Ischnochiton Magdalensis , lids., Fig. 8 , PL 
XI, Lean Chiton, is very common, and may be 
found abundantly by turning over stones at low 
tide. It is long and lean, as its name implies. 
The valves are light colored, spotted without, and 
wldte within. The grayish mantle is set with 
minute scales. It varies in length from one to 
three inches. 
Mopalia muscosa , Gld., Fig. 4, PL XI, Mossy 
Chiton, is common all along the west coast of 
the United States. It is more compact than the 
last species and the plates are more highly sculp- 
tured. The mantle is set with strong hairs or 
points, like a chestnut bur. Outside, its color 
is dark, but within the valves are of a light green. 
Length, two inches. 
The large chiton shown in Fig. 5, PI. XI, was 
named Katherina Doglasice by Dr. Gray of the 
British Museum, in honor of Lady Katherine 
Douglass, who first sent a specimen to that in- 
stitution. It is now called Katherina tunicata , 
Sby., an older specific name having been discov- 
ered and applied. If we were to put her lady- 
ship’s rather lengthy name into familiar English, 
we could do no better, perhaps, than to call this 
famous mollusk, the Black Katy. Its form is 
well shown in the figure, long and oval. The 
mantle is black and heavy, nearly covering the 
white shell-plates ; the foot is reddish ; common 
length, two to three inches. It may be found 
on the rocks at the entrance to the Golden Gate, 
when the tide is low, but its peculiar home is 
