90 THE NAUTILUS. 
paratively smal]. This is a radical difference, and gives the shell 
quite another aspect, so that there can be no question about its being 
distinct. But V. morsei is also decidedly larger, V. ovata not, or 
little, exceeding two millimers of altitude. 
The species is named in honor of Mr. E. 8S. Morse, who has so 
considerably promoted our knowledge of the Pupidae. 
New Philadelphia, Ohio, Nov., 1894. 
A NEW CHITON FROM CALIFORNIA. 
BY W. HeepALL: 
Genus LEPIDOPLEURUS Risso. 
Section Lepidopleurus ss. Valves adjacent, jugal area obscure, 
not separated from the pleural tracts; lateral areas distinct, or 
feeble, when all the sculpture is feeble. Type Z. cajetanus Poli. 
Mediterranean. 
Section Oldrovdia. Valves separated by narrow extensions of 
the girdle, reaching to the jugum ; jugal area prominent, sculptured 
differently from the pleural tracts and extending in front of them 
between the sutural laminz; lateral areas not differentiated ; valves 
heavy, strongly sculptured. Type L. (0.) percrassus n. sp. 
Lepidopleurus percrassus n. sp. 
Shell solid, strong, small, of a pale pinkish-brown with a darker 
brownish girdle which appears rather narrow in the dry state ; scales 
very minute, partly dehiscent, chaffy, with occasional slender 
spinules resembling hairs; scales on the base crowded, minute, 
sandy; an extension of the girdle is prolonged between the valves 
on each side as far the jugum, the surface of these sinuses is also 
minutely scaly with occasional spinules ; valves thick, white below, 
moderately arched with the prominent jugum forming a sort of keel ; 
near the points of insertion the valves are heavily callous below; 
the sutural lamin are short, smooth and separated at the median 
sinus by a prolongation of the jugum in advance of the anterior 
margins of the pleurve ; sculpture of the jugum consisting of punc- 
tate fore-and-aft parallel grooves with some small elevated transverse 
ridges anteriorly; the rest of the valve has, on each side, six or 
eight vermicular ridges divaricating toward the posterior edge of 
the valve and irregularly corrugated with sharp, fine, elevated 
