Original Description of Spinigeropsis calafia by Squires & Saul:
- "Shell small, fusiform, consisting of 6 1/2 whorls; spire moderately high (about 30% of total shell height), apical angle 40°. Protoconch not preserved. Upper two spire whorls smooth (decorticated?), next two spire whorls cancellate with anterior one (antepenultimate whorl) medially carinate; antepenultimate and all subsequent whorls with two varices, one on left side (outer lip side) of shell; digitations becoming stronger on each succeeding whorl, especially on body whorl. Penultimate whorl medially carinate with a short digitation on each varix. Body whorl tricarinate; cords on carinae, anterior and posterior cords strong, subequal middle cord about half as strong; posterior carina bearing two elongate and somewhat posteriorly directed, spinelike digitations at varices; medial carina with no digitations; anterior carina bearing two very elongate, slightly curved and laterally directed, spinelike digitations at varices. Neck of body whorl with several spiral ribs. Aperture quadrate, inner lip smooth with a thin border. Outer lip coincident with right varix bearing two spinelike digitations. Rostrum moderately short, slightly bent to right and bearing coarse growth lines."
Locus typicus: upper part of Santa Susana Formation, Santa Ynez Canyon area, east-central Santa Monica Mountains, Los Angeles County, California, USA
Stratum typicum: "Martinez Stage", Thanetian, late Paleocene
Measure: 16,5 mm high incl. spire and body whorl; 30 mm wide incl. digitations (holotype)
Spinigeropsis calafia Squires & Saul, 2001; Image from Natural History Museum of Los Angeles County published under Creative Commons license
Etymology: named for the state of California