"Shell translucent white, very thin, glassy, seven-whorled; nucleus white, smooth, two-whorled; spiral sculpture of very fine, faint, irregular spiral lines; transverse sculpture [consists] of the incremental lines and a keel or angulation at the shoulder of the whorl, which is pro¬duced into long, nearly horizontally extended triangular spines, [these] deeply guttered out, and having the upper or posterior side shorter in the direction of rotation than the other, so that looked at from the apex the spines recall the paper whirligigs or wind-wheels used as children's toys. There are six of these spines on the last whorl and 31 on the whole shell figured. Spire elevated; suture distinct, not channelled; aperture narrow, long, angulated at the spine, continuous with the open canal, which is curved to the right; at the left of the canal projects a whorl of three or more tips of antecedent canals (often broken away). Interior of aperture simple, not thickened. Maximum length of shell 17.5 mm; of last whorl 12.3 mm; of aperture and canal 10.0 mm; maximum width of aperture 3.0 mm; of the shell exclusive of spines 6.0 mm; of the whole shell 14.0 mm.

Although the radula is similar to that of species of Trophon, it also resembles that of Typhis and, as in that genus, has an accessory semicircular chitinous jawlike structure that survives treatment with KOH. Most significantly, the radula of "Trophon" actinophorus is almost indistinguishable from that of Murex (Paziella) pazi Crosse, which also has the jawlike structure as in Typhis but without a central cluster of denticles. As the shell of "Trophon" actinophorus is muricoid rather than trophonoid and, indeed, differs from M. (Paziella) pazi chiefly by the absence of spines around the base of the body whorl and by the thin outer lip which apparently does not develop denticles even in large examples, the species is here considered in the subgenus Paziella. The relationship of Paziella and Poirieria cannot be discussed at this time, but the two certainly are very close (see Yokes, 1964).

Originally described from BLAKE stations off St. Croix, Martinique, and Barbados, the range of this species was extended southward to the mouth of the Amazon River by Bullis (1964). The illustrated specimens from Sta. P-984, the larger of which is 27.8 mm in length, confirm Dalls suspicion that his specimen 17.5 mm in length was immature.