274 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Ischnochiton venezius Dali, 1919 
Proceedings of the United States National Museum, 55:509. 
Chiton small, warm yellow-brown with a whitish “bloom,” the girdle 
mottled with brown and white, covered with a pavement-like coating of 
minute rounded scales; anterior valve with 14, posterior with 12, and the 
intermediate valves with one slit at each end; anterior valve nearly semi¬ 
circular, with over 20 radial rows of small pustules; for the rest covered 
with a very minute oblique decussation; posterior valve smaller, with 
mucro low and slightly behind the center, the posterior tract decussated 
minutely and with a few scattered pustules near the margin, the central 
area reticulate; intermediate valves mucronate, minutely decussate; pleural 
tracts with fine low axial threading and punctate interspaces; lateral areas 
with 2 or 3 somewhat irregular radial rows of pustules on a minutely 
decussated ground. Length, 7; width, 3.5; height, 2 mm. (Dali.) 
Type in United States National Museum, No. 216792. Type locality, 
near Venice, California. 
Range. Known only from type locality. 
Ischnochiton lividus Middendorff, 1847 
Beitrage su einer Malacologia Rossica, 1:124; PI. 13, figs. 3, 4. Tryon and Pilsbry, 
Manual of Conchology, 14:76; PI. 6, figs. 22-24. 
Chiton testa externa ovali carinata Iivida. Valva antica, valvarum inter- 
mediarum areis lateralibus et valvae ultimae area postica laeviusculis obso¬ 
lete radiatim striatis.Valvarum intermediarum area centrali et 
valvae ultimae area antica longitudinaliter costulata.Costulae 
rarae subtiles albidae, numero 18 ad 20 quarum imprimis medianae et prae- 
cipue ubi postica versus valva in mucronem brevem protracta, sub lente 
tuberculiferae vel quasi e tuberculorum contiguorum serie confluente, ex- 
ortae.Mucro valvarum intermediarum et valvae ultimae antice 
in partem glenoidalem prominulam ulrinque incisura parvula praecise limi- 
tatam, exit.Valva antica dentibus marginalibus 9.Striis 
radiatis obsoletis circiter 14.Valva ultima, margine postico con- 
vexo, dentibus 14. Pallium marginale nudum epidermide glaberrima. Bran- 
chiarum series ante initium secundae tertiae partis totius corporis longi- 
tudinis inserta, ad vicinitatem ani usque pergit.Lamellulae bran- 
chiales numero 26. Longitudo adulti, 0.23 decim. (Middendorff.) 
Shell elevated, tegmentum smooth, shining, livid. Anterior valve, lat¬ 
eral areas, and posterior valve obsoletely radiately rib-striate. Central areas 
longitudinally costulate, the riblets separated, sharply cut, whitish, 18-20 
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