CLASS GASTROPODA 
291 
solid; sinus notched at sides. Girdle leathery, with a few deciduous hairs, 
but no pores. 
This genus closely resembles in sculpture as well as structural charac¬ 
ters Chaetopleura Shuttlew., differing only in the posterior position of the 
mucro and the consequent throwing forward of the tail-valve insertion 
teeth—characters of not great importance. The slits correspond in position 
to nothing in the external sculpture. The girdle is decidedly like Chaeto- 
pleura, being very sparsely hairy (or smooth) and lacking all appearance 
of pores. (Tryon and Pilsbry, Manual of Conchology.) 
Type. P. lanuginosus Carpenter. 
Distribution. San Diego, California, to Point Abreojos, Lower 
California. 
Pallochiton lanuginosus (Carpenter MS) Dali, 1879 
Proceedings of the United States National Museum, 1:297; PI. 3, fig. 21 and 4:287. 
Tryon and Pilsbry, Manual of Conchology, 14:257; PI. 56, figs. 1-11. 
Minor lateral normal, bi-alate; major lateral tridentate, shaft normal. 
(Dali.) 
Shell oblong or ovate, rather elevated, carinated, the side-slopes nearly 
straight. Surface lusterless, color very variable; sometimes dull brown or 
purplish-brown; sometimes green along the ridge and purple or lilac 
dotted with black or olive at the sides; or having the sides of some valves 
scarlet to even snow-white. The median valves are rather acutely beaked 
in the young, beaks eroded in old specimens. Lateral areas but little raised, 
sculptured with gem-like pustules scattered irregularly on a flat (micro¬ 
scopically puncticulate) ground; the pustules often few, rarely wanting on 
some valves; central areas sculptured with many closely beaded longitudinal 
threads, which converge slightly at the ridge, and diverge toward the outer 
sides of the valves; on the second valve they diverge at the ridge. Head 
valve pustulose like the lateral areas. Tail valve much depressed, the 
mucro at the posterior end; anterior area wide, sculptured like the central 
areas; posterior area very narrow, vertical, sometimes pustulose. Interior 
bluish-white, darker at jugum and posteriorly; rarely flesh or pink tinted. 
Sutural plates very broad; sinus narrow, deep, angular and notched at the 
sides. Anterior valve having 8-9, central 1 slit, the teeth long, sharp, a little 
rugose outside; posterior valve having 10-11 slits, the teeth chisel-shaped, 
strongly directed forward, smooth and rather sharp. Eaves of anterior and 
median valves narrow, of posterior valve wider, solid. Girdle rather 
fleshy, leathery when dried, somewhat encroaching at the sutures, and 
smooth or clothed with sparse delicate hairlets. (Tryon and Pilsbry, Man¬ 
ual of Conchology .) 
[893 ] 
