MA2ATLAN UNIVALVES 347 



brown ; (not with red as in the Sitcha analogue, C. modesta ; 

 which it so greatly resembles in general form that Mice, 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 sculptured 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 shell, which is then somewhat glossy ; or (in 

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

 is much excavated, even in young 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 

 yellow 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 well defined ; outside 

 with very irregular lines of growth ; inside with the muscular 

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

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

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

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

 swollen sp. measures long. '6, long. spir. '24, lat. '46, div. 80. 

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



Sab. 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 3f 



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. 1643, 8 do. form L. conspersa, Phil. 



Tablet 1644 contains 7 sp. very much 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 irregular, 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. 



