188 Nelson on Tertiary Mollusca of Peru. 



Crucibulum marine, sp- nov. 



Most of the specimens of this genus are also casts, but a fortunate 

 break laid open the interior of one and showed the " cup " of a Crucib- 

 ulum. The shell is oblong-oval, twice as long as high, and smooth 

 externally, thus diifering from all known species of the West Coast. 

 The cup is large, semi-lunar, and apparently strongly attached to the 

 shell along the whole of the convex side. On the free margin the cup 

 is depressed, with a shallow sinus similar to that in C spinosus Sby, 



The following are the approximate measurements: shell, length 

 24 raillim. ; height 11*6 )nillim ; cup, length 13'4; he?ght 8 millim. 



Vermetus, sp. ind. 



I refer to this genus, doubtfully, a mass of irregular tubes which 

 may, perhaps, be those of a species of Serpula. In the size of the tubes 

 and manner of growth it resembles somewhat the species now living 

 on the West Coast, but no characters remain for identification. The 

 size of the tubes varies from six to eight millimeters. 



Turritella plana, sp. nov. 



Shell elongated, turreted, with from 13 to 19 (?) nearly flat whorls, 

 gradually tapering to a point. Whorls flat above, slightly convex 

 below, marked by fine, equal revolving lines, 20 to 25 in the space of 

 5 millim. Sutures deeply impressed and broad. Two lower whorls 

 much more convex than the upper ones ; revolving lines stronger and 

 crossed by distinct lines of growth. 



I have not seen a perfect specimen of this very interesting species, 

 and hence measurements and the number of whorls can only be given 

 approximately. A specimen consisting of the 8 lower whorls gives 

 the following measurements: length 117*4 millim.; breadth 34'6 mil- 

 lim.; breadth of upper whorl 13*4 millim. A fragment belonging appa- 

 rently to the same specimen gives for the length of the ui^per seven 

 whorls 35 millim. 



The species may easily be distinguished from any with which it 

 might otherwise be confounded, by its nearly flat whorls and equal, 

 thickly crowded, revolving lines ; its impressed sutures ; and the con- 

 vexity of the two lower whorls. 



Turritella snturalis, sp- nov. 



Shell turreted, whorls twelve to fifteen; upper ones regularly con- 

 vex ; lower ones most convex about one-fourth from the bottom of the 

 whorls ; marked by four to seven strong, sharp revolving lines, which 

 are strongest on the lower whorls. Above and below the point of 



