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 striae, diagonal over the areas, longi- 

 tudinal over the rest. The marginal scales- are much larger in 

 proportion, and are bounded by a row 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. 

 Hob. 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, '04 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. LOPHYEUS STEIATO-SQUAMOSUS, n. S. 



L. t. subrotundatd, depressd (ad anqulam 140V, pallidefusco- 

 olivaced ; valvis totd superficie dense granulatis ; areis laterali- 

 bus satis distinctis ; valvis latis, vix curvatis s vix mucronatis ; 

 jugo vix distincto, tenuissime longitudinaliter striato ; marginibus 

 later alibus planatis : mucrone superior e, vix distincto ; limbo 

 pallii squamis solidis, ovalibus, magnis, haud confertis, instructor 

 squamulcB cujusque dimidio alte striato ; marginibus valvarum 

 serratis, fissuris in valvis intermediis una in latere utroque, in 

 valvis terminalibus circiter xii. j valvarum lobis magnis, valde 

 arcuatis. 



