CLASS GASTROPODA 
141 
well-defined. Base of the last whorl very short, well-rounded, marked by 
the faint continuations of the axial ribs and about 15, well-defined, more or 
less equally spaced, deep, spiral striations with fainter ones between them 
as on the exposed portion of the whorls of the spire; the first deep basal 
spiral striation and the one above the suture are some little distance apart 
and mark a plain band excepting the fainter sculpture. Aperture quite 
large, subquadrate; columella short, somewhat twisted, revolute. (Dali 
and Bartsch.) 
Type in United States National Museum, No. 162679. Type locality, 
Station 2902, off Santa Barbara, California. 
Range. San Luis Obispo to San Diego, California. 
Turbonilla auricoma Dali and Bartsch, 1903 
Plate 53, figs. 5, 5a 
Memoirs of the California Academy of Sciences, 3:274; PI. 1, figs. 4, 4a. Bulletin 
68, United States National Museum, 100; PI. 9, figs. 5, 5a. 
Shell slender, attenuated, brown, lighter on the early whorls, becoming 
dark on the last. Nuclear whorls two and one-half, large, helicoid, not im¬ 
mersed, projecting somewhat beyond the outline of the spire, their axis 
being at a right angle to the axis of the later whorls; post-nuclear whorls 
at first somewhat rounded, later flattened, marked by well-developed, rather 
strong, retractive axial ribs, of which 16 appear upon the third and fourth, 
18 upon the fifth to eighth, 20 upon the ninth, 22 upon the tenth, and 30 
upon the penultimate turn. Intercostal spaces a little wider than the ribs 
on all but the penultimate whorl; on this they are somewhat narrower, 
crossed between the sutures by nine subequally spaced, almost equally 
strong, spiral lines of pits, which pass up on the sides of the ribs but do 
not cross their summit. Periphery and base of the last whorl inflated, well- 
rounded, marked by the continuations of the axial ribs, which extend al¬ 
most undiminished to the umbilical area and eight equally strong and almost 
equally spaced, well-incised spiral lines. Aperture ovate; posterior angle 
acute; outer lip thin, showing the external sculpture within, the spiral 
markings appearing as red threads; columella slender, rounded, reflected, 
the reflection giving the base an umbilicated appearance; the parietal wall 
covered by a strong callus. Length, 7.2; diameter, 1.9 mm. (Dali and 
Bartsch.) 
Type in United States National Museum, No. 106511. Type locality, 
Scammons Lagoon, Lower California. 
Range. San Pedro, California, to Scammons Lagoon, Lower Cali¬ 
fornia. Fossil: Post-Pliocene—San Diego, California. 
[439] 
