CLASS GASTROPODA 
57 
base there are four more, closer and diminishing toward the axis; aperture 
rounded, outer lip thin, deeply, widely, retractively arcuate, inner lip with 
a glaze of enamel, pillar lip slightly thickened and at the anterior end a 
little produced; the interior of the aperture is smooth and there is no 
umbilicus. Height of (decollate) shell, 35; of last whorl, 14; diameter, 
13 mm. (Dali.) 
Type in United States National Museum, No. 224134. Type locality, 
off the Pribilof Islands, Bering Sea, in 51 fathoms. 
Range. Mouth of the Colville River, Arctic Alaska, Pribilof and Uni¬ 
mak Islands. 
Tachyrhynchus stearnsii Dali, 1919 
Proceedings of the United States National Museum, 56:347. 
Shell small, slender, acute, white or pale brownish, with a minute sub- 
globular nucleus and about ten subsequent, well-rounded whorls, regularly 
increasing in size; suture distinct, not appressed; spiral sculpture of (on 
the spire, three; on the last whorl, four) low prominent lines about equally 
spaced above the base, and minute, almost microscopic, close-set spirals in 
the interspaces and on the convexly rounded base; axial sculpture not 
perceptible; aperture rounded, simple, the outer lip somewhat arcuate, the 
body thinly glazed. Height of shell, 13; diameter, 4.5 mm. (Dali.) 
Type in United States National Museum, No. 74014, in Stearns Collec¬ 
tion. Type locality, San Pedro, California. 
Range. Known only from type locality. 
Tachyrhynchus pratomus Dali, 1919 
Proceedings of the United States National Museum , 56:347. 
Shell small, yellowish white, acute, with a glassy swollen nucleus of 
about one whorl and six subsequent whorls; suture distinct, not deep, 
axis imperforate; early whorls moderately convex, the periphery nearer 
the succeeding suture, with numerous low, rounded, rather irregular ribs 
extending from suture to suture, with subequal interspaces; these ribs 
become gradually obsolete on the later whorls; spiral sculpture of low, 
irregularly distributed, partially obsolete threads, with minute threadlets 
between them; this sculpture covers the entire whorl; base convexly 
regularly rounded with no umbilical depression; aperture ovate, simple, 
the lips sharp, with no callosities on the body. Height, 10; diameter, 4 mm. 
(Dali.) 
Type in United States National Museum, No. 219369. Type locality, 
Semidi Islands, Alaska, at Station 1152, in 20 fathoms. 
Range. Semidi Islands, Alaska, to Lower California. 
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