(_c_) The _Taenioglossa_ comprise 46 families in all, of which the most important are Tritonidae, Cassididae, Cypraeidae, Strombidae, Cerithiidae, Turritellidae, Melaniidae, Littorinidae, Rissoidae, Paludinidae, Ampullariidae, Cyclophoridae, Cyclostomatidae, and Naticidae. The radula is characterised by a central tooth of very variable form, the prevailing type being multicuspid, the central cusp the largest, on a rather broad base; a single lateral, which is often a broad plate, more or less cusped, and two uncini, rather narrow, with single hooks, or slightly cusped. The accompanying figures of _Cassis_, _Vermetus_, and _Cypraea_, and those of _Littorina_ and _Cyclophorus_ given on pp. 20, 21, are good examples of typical taenioglossate radulae. [Illustration: FIG. 126.--Four rows of teeth from the radula of _Vermetus grandis_ Gray, Andamans. × 40.] In _Homalogyra_ the radula is much degraded, the central tooth is large and triangular on a broad base, the lateral is represented only by a thin oblong plate, and the uncini are absent. In some species of _Jeffreysia_ the uncini are said to be absent, while present in others. _Lamellaria_ has lost both its uncini, but the radula of the allied _Velutina_ is quite typical. A peculiar feature in this group is the tendency of the marginals to increase in number. A stage in this direction is perhaps seen in _Ovula_, _Pedicularia_, and the _Cyclostomatidae_. Here the outermost of the two marginals is by far the larger and broader, and is strongly pectinated on its upper edge; in the _Cyclostomatidae_ the pectinations are rather superficial; in _Ovula_ (where both marginals are pectinated) they are decidedly deeper; in _Pedicularia_ they are deeper still, and make long slits in the tooth, tending to subdivide it altogether. In _Turritella_ the number of marginals is said to vary from none (in _T. acicula_) to three (_T. triplicata_), but the fact wants confirmation. _Solarium_ is an aberrant form, possessing simply a number of long uncini, which recall those of _Conus_ or _Pleurotoma_, and is therefore hard to classify; the allied _Torinia_ has a radula which appears allied to _Ovula_ or _Pedicularia_. In _Triforis_ the teeth are identical throughout, very small, about 27 in a row, tricuspid on a square base, cusps short. The normal formula of the _Taenioglossa_ is 2.1.1.1.2; in _Lamellaria_, 1.1.1; in _Triforis_, 13.1.13, or thereabouts. [Illustration: FIG. 127.--Two rows of the radula of _Cypraea tigris_ L. × 30.] [Illustration: FIG. 128.--Portion of the radula of _Ianthina communis_ Lam. × 40.]