ISCHNOCHITONIDAE 3 2 1 



% to /4 inch in length, oval. Moderately sculptured and without very 

 distinct lateral areas. It has microscopic, even, quincunx pittings on the upper 

 surfaces of the valves. End valves with concentric rows of fine, low beads. 

 Lateral areas with fine, wavy, longitudinal, incised lines. Posterior slope of 

 posterior valve is concave and with 9 slits. Color whitish with heavy mottlings 

 of olive-green; rarely with white spots. Girdle narrow, colored with alter- 

 nating bars of white and greenish brown. Scales like microscopic split peas 

 which are finely striated. A fairly common shallow-water species. 



Ischnochiton magdalenensis Hinds Magdalena Chiton 



Coos Bay, Oregon, to Lower California. 



2 to 3 inches in length, elongate. Color a drab greenish, commonly 

 whitish due to wear. Central areas with fine, irregular, longitudinal cuts 

 and with diamond-shaped pits near the lateral areas. Lateral areas prominently 

 raised and with 10 to 12 coarse, radial ribs of gross, low beads. Front slope 

 of anterior valve straight. Interior of valves bluish with the posterior end of 

 each whitish. Girdle rather narrow and with alternating, faint bars of 

 brown and yellowish brown. Scales round and so small that the girdle has 

 the texture of fine sandpaper. Common. 



Ischnochiton conspicuus Pilsbry Conspicuous Chiton 



San Miguel Island, California, to the Gulf of California. 



2 to 6 inches in length, very similar to magdalenensis, but the front slope 

 of the anterior valve is very concave; the central areas are practically smooth 

 and with flecks of green. Scales are elongate, hard, and so densely packed that 

 the girdle feels velvety. Interior of valves pinkish and blue. Moderately 

 common between tides. 



Ischnochiton acrior Pilsbry Acrior Chiton 



San Pedro, California, to Lower California. 



2 to 6 inches in length, very similar to magdale7iensis. Instead of dia- 

 mond-shaped pittings on the sides of the central areas, there are wavy ribs. 

 The front slope of the anterior valve is very concave, as in conspicuus. The 

 scales are similar to those in inagdalenensis, but much larger. Interior of 

 valves pinkish with a blue spot at the anterior end of each valve. Moderately 

 common. 



