192 MAZATLAN UNIVALVES 
albolineate or quite black. Normally there is a black line on 
the ridge, bounded by two white ones; diagonal areas and 
terminal valves white, penciled with brown in finely waved 
transverse lines. Besides the colour, shape and delicate tex- 
ture, it differs from the young of L. articulatus in the following 
particulars. Surface (under the microscope) regularly granu- 
lated in diagonal rows ;_ granules larger in proportion. Radia- 
ting lines of punctures almost always visible within. Plates of 
insertion in simple rows, not plumed. Sinus with irregular 
transverse incisions internally. Substance of valves next the 
lobes with a row of larger cells. Scales of margin more grey. 
rounder, more deciduous.—In the young shell, the granules on 
the diagonal areas are much larger in proportion. In addition 
are seen extremely fine strie, diagonal over the areas, longi- 
tudinal over the rest. The marginal scales are much larger in 
proportion, and are bounded by arow of gill-like hairy pro- 
ceses, as in the young of the last species.—The largest specimen 
measures long. 1°8, lat. *9, div. 115°. 
Hab.—Mazatlan ; Belcher.—Do.; rare; L’pool Col. 
Tablet 894 contains 3 extremely young specimens, the small- 
est ‘18 in length. In one, most of the valves are separate, 
displaying the same structure as in the adult. The mantle 
shews clearly the marks of insertion; and, with the dried 
remains of the animal, is so transparent that the lingual ribbon 
is clearly traceable within, ‘O04 by *0075 in. 
Tablet 895 contains three specimens; the largest, one with 
the margin perfect, and one with black valves intercalated.— 
896, 2 sp. with the valves separate, and 2 nearly black valves 
to shew structure. 
250. LopHYRUS STRIATO-SQUAMOSUS, 7%. S. 
Lt. subrotundatd, depressa (ad angqulam 140°), pallide fusco- 
olivaced ; valvis tota superficie dense granulatis ; areis laterali- 
hus satis distinctis ; valvis latis, vie curvatis, vix mucronatis : 
jugo vie distincto, tenvissime longitudinaliter striato ; marginibus 
lateralibus planatis : mucrone superiore, vix distineto ; limbo 
pallii squamis solidis, ovalibus, magnis, haud confertis, instructo. 
squamule cujusque dimidio alte striato; marginibus valvarum 
serratis, fissuris in valvis intermediis und in latere utroque, in 
valvis terminalibus circiter xu.; valvarum lobis magnis, valde 
arcuatis. 
