374 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV. 
liquely sloping ridge parallel with the incremental sculpture often 
connects the alternate nodes on the sutural ridge with the nodes on 
the upper angle; between the lower angle and the umbilical region 
on the body whorl are 6 or 7 revolving ridges, the first and the most 
prominent, slightly tuberculated, the others diminishing in import- 
ance and nodosity and in distance apart as the umbilical region is 
approached; the surface of all the whorls is crossed by numerous fine 
incremental lines which ‘slope downward and backward from the 
upper margin, at an angle deflecting about 25° from the vertical; 
aperture subcircular; lip simple; character of shell material, nacre- 
ous, over which in the well-preserved fragments is a horny epidermis 
in which the nodes of the underlying layer are somewhat exaggerated. 
Dimensions.—Of type (restored), altitude, 835 mm.; latitude, 35 
mm.; apical angle between 85° and 90°. 
Notes.——This magnificent species is apparently the precursor of 
T. bard Dall, now found living off the California coast; it differs 
from the latter in its more angular whorl and more tabulate upper 
portion of the whorl, in its less conspicuous nodes on the sutural 
carina, in its stronger revolving basal ridges, and in minor points in 
the secondary sculpture. 7’. santacruzana is much smaller and rela- 
atively shorter than 7’. columbiana Dall from the Eocene of Rock 
Creek, Columbia County, Oregon, and has an entirely different 
arrangement of the nodes and revolving ridges than the latter. 
Named for the Santa Cruz quadrangle, in which it has so far only 
been found. 
Type.—slightly decolleté specimen, Cat. No. 165,442; U.S.N.M. 
(Locality No. 100.) | 
~ Horizon.—San Lorenzo formation, Oligocene. : 
Localities.—Santa Cruz quadrangle, Santa Cruz County, locality 
No. 100, on San Lorenzo River, 3 miles above the town of Boulder 
Creek, abundant; locality No. 102, San Lorenzo River, 54 miles north 
of Boulder Creek. (R. Arnold, R. Anderson.) 
Genus ARCHITECTONICA Bolten. 
ARCHITECTONICA LORENZOENSIS, new species. 
Plate XX XIII, fig. 10. 
Description.—Shell spiral, conical, depressed, attaining a diameter 
of 20 mm.; spire low, whorls 5 or 6, quite evenly but moderately con- 
vex; suture deeply impressed. Upper whorls ornamented by 3 raised 
spiral lines; body whorl biangular, the two angles being close to- 
gether and each bearing a rounded revolving rib; upper surface of 
body whorl bearing an impressed groove near the suture and between 
this and the periphery 2 quite prominent raised lines and 1 or more 
subsidiary revolving strive; base very slightly convex, carrying a 
