Echinophoria superficially resembles Galeodea, in having a short spire and a large, inflated last whorl, prominent spiral sculpture at least on the early spire whorls, a spiral row or several rows of prominent nodules at least at the periphery, and descending below the periphery on the last whorl of most specimens of some species, and in having a thickened and narrowly but prominently reflected terminal varix. However, it differs from Galeodea in a number of significant characters. The most obvious is in having a much more strongly twisted anterior siphonal canal, deeply notched (in the antero-posterior direction) at the dorsal anterior end so as to generate a prominent siphonal fasciole, which on all the Recent species of Echinophoria bears a prominent, narrow ridge on the posterior (adapical) side and is separated from the previous whorl by a narrow, deeply and evenly concave groove. The shell shape of species assigned to Echinophoria also is distinctive, as its consistent, even, marked inflation produces a teleoconch that is more nearly spherical than those of most Galeodea species. The anterior siphonal canal is scarcely visible in conventional apertural view, contrasting with the obvious canal of Galeodea species, and contributing further to the subspherical appearance. The protoconch of Echinophoria is low-turbiniform, with a well-impressed suture and about 3 strongly inflated, smooth whorls. The subfamilial character of a fan-shaped operculum, with the nucleus in the centre of the left (columellar, adaxial) edge, also distinguishes Echinophoria effectively from Galeodea, which has its opercular nucleus at about a third to half of the opercular height from the anterior end of the right (outer lip, abaxial) edge of the operculum. The animal of E. wyvillei investigated here also differs from that of all Galeodea and Oocorys species investigated in having the mantle cavity organs situated markedly further back in the mantle cavity. It seems quite feasible that Echinophora, along with the other taxa here referred to Phaliinae, evolved from quite a different early tonnoidean ancestor from that of the Cassinae, i.e., the shell shapes of Galeodea and Echinophoria might well be convergent rather than closely related phygenetically.
The protoconch, siphonal canal, apertural characters and shell shape of Echinophoria are closely similar to those of species of Phalium and Semicassis. Phalium is distinguished from Echinophoria by lacking the many prominent nodules, other than a peripheral row present in some species, by having axial and spiral sculpture both fine but more-or-less equally well developed (whereas axial ridges and grooves are weak in Echinophoria), by retaining varices at all growth pauses, unlike all other genera of the subfamily, by having a better-developed ventral apertural callus shield, by the shell shape being narrower and more elongate than in most species of Echinophoria or Semicassis, and by most species having sharp nodules or small spines around the outer edge of the anterior half of the outer lip. Such nodules around the outside of the terminal varix are present also in some of the species referred by Abbott (1968) to Casmaria, and low, weak nodules are present on the exterior of the lower part of the outer lip in some specimens of the kurodai form of Echinophoria wyvillei (Watson), but they are not present in the other members of the subfamily. Semicassis is distinguished from Echinophoria by having dominantly spiral sculpture, forming prominent, strap-like cords in many species, and by lacking nodules other than a peripheral row in most specimens of most species. Semicassis differs from Phalium in having a more weakly developed ventral callus shield (similar to that of Echinophoria), in lacking obvious axial sculpture (other than the nodules, which are axially aligned in some species), and in retaining only the terminal varix, except in a few individuals. Semicassis differs less obviously from Casmaria, as used by Abbott (1968). Several of the smaller, more elongate, more weakly sculptured species of Semicassis, such as S. bulla Kuroda in Habe, 1961 (Japan) and S. glabrata (Dunker, 1852) (western Pacific), very closely resemble some of the smaller, more weakly sculptured, and more elongate species referred by Abbott (1968) to Casmaria, such as G cernica (Sowerby, 1888) (Mauritius), C. nipponensis Abbott, 1968 , C. perryi (Iredale, 1912) (southwest Pacific to Easter Island; Philippines, Japan, ?western Atlantic - Parth 2000). These small, elongate species referred to Casmaria lack nodules on the outside of the anterior half of the terminal varix, and seem better referred to Semicassis. This would leave only the abundant, widespread, tropical species C. erinaceus (Linne, 1758) and C. ponderosa (Gmelin, 1791) in Casmaria, along with the eastern Pacific species C. vibexmexicana (Stearns, 1894). Anatomical and radular characters need to be compared to determine whether Casmaria and Semicassis are distinct genera.
Abbott (1968) listed Trachydolium in the synonymy of Echinophoria, but Howe (1926: 303) merely listed the name "Trachydolium dalli" in a table, with no description and no bibliographic indication of which species he meant. Abbott (1968) apparently assumed that Howe was referring to Galeodea dalli Dickerson, 1917, which occurs in Oligocene rocks in the area described by Howe. Although Abbott's interpretation is reasonable, this identification cannot be determined from Howe's (1926) paper alone. Trachydolium Howe, 1926 is a nomen nudum.
Finlay (1926: 230) proposed Euspinacassis with a combined description oiil Euspinacassis pollens n. gen., n. sp.", but then went on to include two further species in the new genus. Finlay undoubtedly intended the heading to indicate that E. pollens is the type species, but Abbott (1968: 95) stated that the type species of Euspinacassis was selected by Powell's (1928: 631) subsequent designation. However, the Code (ICZN 1999: Article 68.2.1) states unequivocally that "the expressions "gen. n., sp. n.", "new genus and species", or an equivalent", applied before 1931 to only one of the included species, is an original type species designation "if no other type species was explicitly designated", and this clearly covers the case of Euspinacassis; E. pollens is the type species by original designation. Rutsch (1931) pointed out that, despite Finlay's (1926) statement to the contrary, the correct genus for these New Zealand species is Echinophoria Sacco, 1890.
The species-level taxonomy of the Recent species of Echinophoria has received widely differing treatment from different authors. Pain & Cox (1988) advocated the recognition of only three species, E. coronadoi (= Cassis wyvillei; = Bathygalea pilsbryi), E. carnosa and E. kurodai, although they later (Pain & Cox 1990) conceded that E. bituberculosa is a species of Echinophoria. In contrast, Kreipl (1997) recognised all the named Recent forms as distinct species. Abbott (1968) followed an intermediate approach, recognising the western Pacific form Cassis wyvillei as a geographic subspecies of E. coronadoi. Mühlhausser (1992) later added the species E. oschei, from Mozambique, East Africa; he thought it most nearly similar to E. bituberculosa. Comparison of the MNHN material, including the holotype of Cassis coronadoi, with the illustrations by Woodring& Olsson (1957), Abbott (1968), Bayer (1971), Pain & Cox (1988,1990), Mühlhausser (1992) and Kreipl (1997) resulted in the recognition of most Recent taxa as distinct species, but also in the synonymy of several species recognised by Abbott (1968) and several later authors, such as Mühlhausser (1992).