194, MAZ7ATLAN UNIVALVES 
Genus LEPIDOPLEURUS, Risso. 
Hf. § A. Ad. Gen. vol. i. p. 471.—Ischnochiton, Gray, Proc. 
Zool. Soe. 1847, p.126. Mantle scales very minute, grooved : 
insertion-plates thin, smooth-edged. 
252. LEPIDOPLEURUS SANGUINEUS, Rve. 
Chiton sanguineus, Rve. Conch. Ic. pl. 17, f. 98. 
Comp. Chiton limaciformis, Sow. Proc. Zool. Soc. 1832, p. 26:— 
Conch. Ill. sp. 58, f. 38.—Rve. Conch. Ic. pl. 8, sp. 42. (Co- 
lumbia, Sow. : Inner Lobos Is., Peru, and Guacomayo, under 
stones at low water, Cuming.) 
This 1s probably not the Ch. sanguineus of Guilding, from 
St. Vineent’s, which is quoted by Reeve in the Conch. Ic. : 
and is certainly not the Ch. sanguineus of Dr. Cutting, from 
Barbadoes, in the Bristol Museum. It is however identical 
with the specimens in the Cumingian collection, and most 
closely resembles Ch. limaciformis. There may be a difference 
in the integument, which the imperfect state of the specimens 
has failed to display. The Mazatlan shells are more generally 
tuberculated on the terminal valves than on the typical speci- 
mens of the species. 
The mode of attachment is quite different in this shell from 
that of Lophyrus. The valve margin has an outer and an 
inner rim ; the outer being a simple continuation of the exter- 
nal shell layer; the inner being a white, sharp ridge, cut by 
10—14 slits in the terminal valves; so as to give the appear- 
ance of a lip with a row of incisor teeth within. The central 
valves have one slit. The radiating punctures are elongated. 
Inside rose-coloured; outside brownish pink, or dark olive 
green, or brown, or yellowish irregularly spotted with green. 
Surface deeply furrowed with irregular longitudinal lines, 
waved at the sharply angular diagonal lines. The terminal 
valves are tuberculose, finely so above, coarsely below. Interior 
surface finely corrugated and ridged for the muscular attach- 
ments. Valve lobes small, arched; sinus very large. The 
valves are easily loosened from the membrane, which is 
generally thin and smooth, sometimes with an irregular whitish 
deposit, apparently not of organic matter. Long. 1°04, lat. °4, 
div. 105°. 
Hab.—Mazatlan ; very rare; L’pool Col. 
Tablet 899 contains 4 sp. various colours.—900, 2 sp. opened 
to shew the valves. 
