MOLLUSCA OF PORTO RICO. 
451 
Subemarginula notata Linnaeus. 
Patella notata Linnseus, Syst. Nat., ed. x, p. 784, 1758. 
Subemarginula notata P ilsbry, Man.,xn, p. 282, pi. lxiy, figs. 34, 35, 1890. 
San Juan, Porto Rico (Gundlach). 
Subemarg-inula rollandii Fischer. 
Emarginula rollandii Fischer, Journ. de Conchy., v, p. 356, pi. xii, fig. 10, 1856. 
Shell small, oval, with the apex subcentral, recurved, sculptured with unequal, radiating ribs, and 
crossed by coarse, low, concentric cords; anterior fissure deep, straight, its sides nearly parallel. Color 
white, greenish or pinkish; interior whitish, with white rays. 
Length, 8; width, 6.5; height, 3 mm. 
Ensenada Honda, Culebra, one specimen. 
Subclass AMPHINEURA. 
Order P0LYPLAC0PH0RA. 
Mollusks whose dorsal surface bears eight imbricating shelly plates embedded in an outer zone 
or girdle; head divided from the body; gills numerous, occupying a groove on each side between the 
foot and mantle; foot adapted to creeping. 
Family LEPIDOPLEURID/E. 
Genus LEPIDOPLEURUS Risso, 1826. 
Girdle with minute, gravelly, smooth or striated scales, usually with a fringe of longer scales, 
valves without insertion plates, or with the inserted margin entire. 
Lepidopleurus pergranatus Dali. Plate 58, figs. 1, ct-c. 
Leptochiton pergranatas Dali, Blake Report, ii, p. 414, 1889. 
Shell elongated, slightly elevated, regularly arcuate, without a jugum; valves wide, without 
apices; front and back valves more or less concave; posterior valve without elevated apex. The whole 
surface of the shell is covered with close, granular sculpture; the lateral areas slightly raised, and in 
addition to the granulation sculptured with curved furrows which become fainter on the central areas 
and are carried around parallel with the sides and back of the valves. Girdle wide, covered with 
delicate scales; entire shell waxen or white. 
Length, 12; breadth, 6.5 mm. 
Off San Juan, Porto Rico; also near Dominica, in 138 fathoms. 
Family CHITONIDA. 
Subfamily ISCHNOCHITONIN^E. 
Genus CHIETOPLEURA Shuttleworth, 1853. 
Valves external, having sharp, slit insertion plates (at the place of insertion of the girdle); girdle 
leathery, more or less hairy; gills extending almost or entirely to the front end of the foot. 
Chsetopleura janeirensis Gray. 
Chiton janeirensis Gray, Spic. Zool. , p. 6, pi. in, fig. 8, 1828. 
Shell oblong, elevated, rather narrow; dorsal ridge somewhat angular, ashen, olive or brownish, 
strongly sculptured; the mucro in front of the middle, rather prominent; lateral areas strongly elevated, 
sculptured, with four coarse, granose ribs; anterior valve having eleven to eighteen such ribs; central 
areas with about twelve granose, acute threads on each side of the jugum; girdle with a few short, 
delicate hairs. 
Length, 18; diameter, 9 mm. 
Ensenada Honda, Culebra. 
