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 luies. Besides the colour, shape and delicate tex- 

 ture, it diifei's 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 irregidar 

 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 yoimg shell, the granules on 

 the diagonal areas are much larger in proportion. In addition 

 are seen extremely fine stria;, 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, led. '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 clearl;f traceable within, 'Ol bj- '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 STHIATO-SQTTAMOSUS, n. S. 



L. t. suhrof/undatd, depress A (ad anqulam 140^, pallidefusco- 

 olivaced ; valvis totd siqjerjieie dense granulatis ; areis laterali- 

 hus satis distinctis ; valvis latis, vix eurvatis, vix mucronatis ; 

 jugo vix distincto, tenuissinie longitudinaliter striato ; marginihwi 

 lateralihils planatis : mucrone superiore, vix distincto ; limbo 

 pallii squamis solidis, ovalibus, magnis, hand confertis, instructo. 

 sqtiamulm cujusque dimidio alte striato ; marginibus valvarum 

 serratis, fissuris iyi valvis intermediis una in latere utroqiw, in 

 valvis terminalihus circiter xii. ; valvarum lobis magnis, valde 

 arcuatis. 



