MA3ATLAN UNIVALVES 347 



brown : (not -witli red as in the Sitclia analogue, C. modesta ; 

 wliicli it so greatly resembles in general form that Mke. not 

 unnaturally mistook them, but which is put in another sub- 

 generic group by Messrs. Adams.) The shape varies from a 

 type even more inflated than L. puncticulata, Phil, to one 

 more elevated than his L. conspersa, with every gradation 

 between. The surface is either sculptiired with prominent 

 (though not sharp) ribs, with very broad interstices ; or with 

 smaller and very close ribs, with narrow interstices : or else 

 the interstices degenerate into fine lines cut on the smooth 

 surface of the sheU, which is tlien somewhat glossy ; or (in 

 the young state) it is quite smooth and polished. The columella 

 is much excavated, even in youjig shells. The mouth is gene- 

 rally of a rich, lustrous brown within, more or less in bands, 

 with dots inside the labrum ; but sometimes it has only the 

 yeUow of the exterior more developed. The nuclear whirls 

 are of a purplish brown, (sometimes light) of chalcedonic tex- 

 ture as in Terebra, and very rarely eroded. The operculum is 

 very regular in growth, with the spire weU defined ; outside 

 with very irregular lines of growth ; inside with the muscular 

 scar beautifidly striated spirally. This can be seen by trans- 

 niitted light, and at once separates it from the next species. 

 The young shell is frequently angulated at the base ; and au 

 unusually large rib often marks the periphery in the adult. A 

 swoUen sp. measures long. "(3, long. spir. "24, lat. '46, div. 80". 

 An elongated sp. „ "7, „ '37, „ '43, „ 50". 



ffab. — Real Llejos, Hinds. — Taboga and Panama ; common, 

 chiefly on large fragments of rock at high water mark : 

 C. B. Adams. — Mazatlan; extremely common; L'pool S( 

 Havre Coll. 



Tablet 1638 contains 7 sp. white, very ventricose.— 1639, 9 

 do. rather less, (answering to L. puncticulata.)— 1640, 7 do. 

 ordinary state.— 1641, 7 do. flattened ribs.— 1642, 7 do. more 

 elevated. — 16-1:3, 8 do. form L. conspersa, IPliil. 



Tablet 1644 contains 7 sp. very mucli elevated, yellowish. — 

 1645, 11 do. series from young state "18 by •17.— 1646, 6 do. 

 less elevated. — 1647, 8 do. whirls rounded.— 1648, 7 do. usual 

 shape. — 1649, 7 do. rather flatter. — 1650, 7 do. ventricose. 



Tablet 1651 contains 3 sp. keels distant.— 1652, 4 do. keels 

 very close.— 1653, 3 do. keels somewhat irrogidar, as in Purpura 

 lapillus.— 1654, 4 do. nearly smooth. — 1655, 4 sp. abnormal 

 growth.— Many of the above retain their opercula : tablet 1656 

 contains 9 separate ones. 



