304 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Type in United States National Museum? Type locality, Puget Sound, 
Washington. 
Range. Shumagin Islands, Alaska, to Rosario, Lower California. 
Mopalia muscosa hindsii Reeve, 1847 
Conchologia Iconica , Chiton; PI. 12, fig. 67 a-b. Tryon and Pilsbry, Manual of Con - 
chology, 14:296; PI. 62, figs. 99, 100. 
Chit, testa oblonga-ovata, antice subattenuata, valva antica terminali 
nonafariam carinata, conspicue granato-clathratis, retusa, postica parva, 
umbonata, retusa, caeteris undique diversimodo granato-clathratis, areis 
lateralibus non elevatis, margine antico tenuicarinato; olivaceo-viridi, in- 
terdum luteo-albido variegata; ligamento corneo, setis brevibus sparsim 
obsito. 
Shell oblong-ovate, a little attenuated anteriorly, anterior terminal valve 
nine-keeled, conspicuously granosely latticed, the posterior small, umbo- 
nated, retuse, the rest diversely granulosely latticed throughout, lateral 
areas not raised, distinguished by a fine keel along the front margin; olive- 
green, sometimes variegated with yellowish-white; ligament horny, spar¬ 
ingly beset with short bristles. (Reeve.) 
Type in Mr. Cuming's Cabinet. Type locality, not known. 
Range. Sitka, Alaska, to Gulf of California. 
Described as Chiton hindsii Reeve. 
Mopalia muscosa porifera Pilsbry, 1892 
Tryon and Pilsbry, Manual of Conchology, 14:297; PI. 62, figs. 93, 94. 
The shell is rather small, thin and high, but not to as great an extent 
as M. acuta . It is sculptured as in M. hindsii, but the diagonal and sutural 
ribs are more prominent, and sculptured with strong, transverse beads 
exactly as in M . imporcata, the suture being dentated by them. Color of 
valves olivaceous, clouded obscurely with smoky, and having a black 
stripe each side of the dorsal lighter stripe. The posterior valve has a 
depressed mucro near the posterior margin, which is very slightly waved 
inward. Girdle firm and leathery, minutely and evenly papillose all over, 
blackish with spots of orange; having a small pit or pore at each suture, 
with a series of pores alternating with these a little outside of the middle 
of the girdle. Sometimes some of the sutural pores bear large hairs, 
curling outward; and sometimes some or many of the pores are completely 
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