Figures: 22 A–B urn:lsid:zoobank.org:act: AA00F113-8188-4B1D-A4ED-9D2B17F1A56D
Type locality: S of Kiska Island, Rat Ids., Aleutian Is., Alaska (51°33.71 N, 178°20.98 E) (94-1994-1-165), 470 m, R/ V Vesteraalen (leg. Theresa Turk, 18 July, 1994).
Type: Holotype, LACM 3594 R/ V Vesteraalen (leg. Theresa Turk, 18 July, 1994).
Description: Shell to 46.8 mm, periostracum thin, closely adherent, yellowish green, shiny. Six whorls, protoconch (one whorl), and first two teleconch whorls low; later whorls only slightly inflated; suture moderately deep, channeled by sharp shoulder angulation and narrow shoulder shelf. Early teleconch sculpture of microscopic spiral cords, fading on later whorls. Axial sculpture absent except for growth lines. Spiral sculpture of mature shell of low, mostly slanted, narrow cords, five on penultimate whorl; two or three obsolete cords on base. Aperture a little more than 1/3 of shell height, acutely angled posteriorly, outer lip thickened, inflated, extending below anterior tip of columella; inner lip not projecting, fasciole extending in curve from base of columella to midway across columella; shell surface smooth in advance of aperture.
Radula: Rachidian tooth broad, rectangular, anterior corners rounded, anterior edge indented, posterior edge bearing three short, spaced cusps. Lateral teeth large, tricuspid, outer cusp long, thick, strongly curved; middle cusp short, less than half the length of outer one, slender, set very close to inner cusp; inner cusp thick, about 3/4 length of outer one.
Remarks: This species strongly resembles Sulcosinus taphrium (Dall, 1891) (figs 22 C–E), but differs in 1) the sharp angulation of the shoulder, 2) the lack of a raised, thickened inner lip and 3) lack of microscopic bristles on the periostracum. The Rachidian tooth of S. taphrium has four long cusps compared to three short cusps in S. carinatus.
Etymology: The name emphasizes the precision of the sharply angulate shoulder.
Distribution: Aleutian Islands, S of Kiska Island, 470 m. Known only from the holotype.
Habitat: Unknown, probably volcanic sand and gravel, typical of the area.