368 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV. 
GASTEROPODA. 
Genus J JEU) JRO) WO) Lamarck. 
PLEUROTOMA NEWSOMI, new species. 
IPI SOOS00UL Tike, 2 
Description.—Shell about 12 mm. in length, spindle-shaped and 
exceedingly slender; spire very long and apex acute. “Whorls 6, con- 
vex, sharply angulated, the angle carrying a very prominent, rounded 
revolving rib; upper and lower surfaces of whorl concave and bor- 
dered by moderately pronounced sutural ridges; body whorl biangu- 
lar, each angle carrying a revolving ridge similar to those on upper 
whorls, the lower ridge being slightly less prominent than the upper; 
below the lower rib is still a third much smaller one; between and 
below the revolving ridges on the body whorl! are several minor raised 
revolving lines (8 between the major revolving lines on the type) ; 
faint indications of spiral lines are also visible on the concave sur- 
faces of the upper whorls. Suture distinct. Aperture subovate. 
Canal long, narrow, nearly straight. 
Dimensions.—Leneth, 12 mm.; latitude, 3.8 mm.; apical angle, 18°. 
Notes.—This species is entirely unlike any previously described 
Pleurotoma from the west coast and is characterized by its exceeding 
slenderness and the prominence of the revolving cord-like ridges. 
The character of the spiral sculpture, especially of the body whorl, 
reminds one somewhat of Perissolax blakei Conrad from the Tejon 
(Eocene). Named in honor of Dr. John Flesher Newsom, of Stan- 
ford University. 
Dy pe. —Cat. No. 165440, U.S.N.M. (Locality No. 107.) 
Horizon.—San Lorenzo formation, Oligocene. 
Locality Santa Cruz quadrangle, Santa Cruz County, iceaity No. 
107, in small ravine off Boulder Creek, 24 miles north of Kagle Rock. 
(R. Arnold, Isaac Anderson. ) 
PLEUROTOMA PERISSOLAXOIDES, new species. 
Plate XXXIII, fig. 13. 
Description—Shell about 28 mm. in length, fusiform; spire well 
elevated; apex moderately acute; whorls at least 5, very angular with 
an exceedingly prominent revolving smooth keel on angle which 1s 
near base of whorl; upper portion of whorl flat or shghtly concave ; 
surface ornamented by microscopic revolving striz and numerous fine 
incremental lines which indicate a very deep narrow sulcus in the 
outer lip just above the keel of the whorl; body whorl carrying a 
second keel less prominent than and below the major keel and distant 
from it about one-sixth the length of the body whorl; suture dis- 
