Fig. 117.—Portion of the radula of Melongena vespertilio Lam., Ceylon. × 30.
Fig. 118.—Portion of the radula of Eburna japonica Sowb., China. × 30.
Fig. 119.—Portion of the radula of Murex regius Lam., Panama. × 60.
(b) The Rachiglossa comprise the 12 families Olividae, Harpidae, Marginellidae, Volutidae, Mitridae, Fasciolariidae, Turbinellidae, Buccinidae, Nassidae, Columbellidae, Muricidae, and Coralliophilidae. Certainly most and probably all of these families are or have been carnivorous, the Coralliophilidae being a degraded group which have become parasitic on corals, and have lost their teeth in consequence. The characteristics of the group are the possession of a central tooth with from one cusp (Boreofusus) to about fourteen (Bullia), and a single lateral more or less cuspidate, the outer cusp of all being generally much the largest. Thus in Melongena respertilio (Fig. [117]) the central tooth is tricuspid, the central cusp being the smallest, while the laterals are bicuspid; in Eburna japonica (Fig. [118]) the central tooth is 5-cusped, the two outer cusps being much the smallest. The teeth, on the whole, are sharp and hooked, with a broad base and formidable cutting edge. In the Olividae, Turricula, Buccinopsis, and the Muricidae the laterals are unicuspid and somewhat degraded (Fig. [119]). In Mitra and the Fasciolariidae they are very broad and finely equally toothed like a comb (Figs. [120], [121]). The whole group is destitute of marginals.
Fig. 120.—Portion of the radula of Imbricaria marmorata Swains. × 80.
