Tripterotyphis lowei norfolkensis: The shell is the smallest in the genus (maximum length 10 mm) and generally biconic. The spire is high, consisting of five weakly subangulate postnuclear whorls and a protoconch of undetermined nature. The suture is obscured. The body whorl is moderately large and trigonal. The aperture is small and ovate, with an erect peristome. The outer apertural margin is strongly, coarsely serrate, the serrations reflecting the spiral cords as they traverse the leading edge of the last varix. Each anal siphonal tube is confluent with a long, broad, posteriorly bent varical spine at the shoulder margin, the spine originating almost midway between varices but terminating slightly closer to the succeeding varix; the cross-sectionally triangular spine then sweeps briefly ventrally and strongly posteriorly, where it meets and encloses the tube. The siphonal canal is broad and closed, except briefly, near its anterior end, where it is sharply dorsally bent. The body whorl bears three broad, winglike varices. Spiral sculpture consists of nine spiral cords, four on the canal and five on the body, these ephemeral between varices and more prominent on them, throwing the varical margin into fine crenulations. A low, oblique ridge extends from each varix, ventrally and anteriorly, to a point just before the next varix. Shell color is translucent off-white to fleshv vellow-brown. The entire shell is covered by a moderately thick, minutely ruffled, flat-white intritacalx.

Tripterotyphis lowei norfolkensis: Known to us from Norfolk Island, the Solomon Islands, and the Philippines.

Tripterotyphis lowei norfolkensis: This species was originally assigned to Pterynotus (Nothotyphis) on the basis of a misconception of its author concerning its manner of varix formation; it is clearly a Tripterotyphis. Recently, Ponder (1972) has reduced this species to a subspecies of T. lowei, an eastern Pacific species. The idea of two forms separated by the entire Pacific Ocean for presumably a considerable period of time and differing (also presumably) only subspecifically is incompatible with our concept of subspecies.