The Cambridge natural history . FiG. 125.—Portion of the radiila of Cassis sulcosa Born., x 40. Tlie marginalsto the right aie not fully drawn. tidae, and JSTaticidae. The radula is characterised by a centraltooth of very variable form, the prevailing type being multi-cuspid, the central cusp the largest, on a rather l)road base ; asingle lateral, whicli is often a broad plate, more or less cusped,and two uncini, rather narrow, with single hooks, or slightly. Fig. 126.—Four rows of teethfrom the radula nf Vcrmetusgrandis Graj, cusped. The accompanying figures of Cassis, Vermctus,
The Cambridge natural history . FiG. 125.—Portion of the radiila of Cassis sulcosa Born., x 40. Tlie marginalsto the right aie not fully drawn. tidae, and JSTaticidae. The radula is characterised by a centraltooth of very variable form, the prevailing type being multi-cuspid, the central cusp the largest, on a rather l)road base ; asingle lateral, whicli is often a broad plate, more or less cusped,and two uncini, rather narrow, with single hooks, or slightly. Fig. 126.—Four rows of teethfrom the radula nf Vcrmetusgrandis Graj, cusped. The accompanying figures of Cassis, Vermctus, andCypraca, and those of Littorina and Cydopliorvs given on , 21, are good examples of typical taenioglossate radulae. In Hoiiialogyra the radula is much degraded, the centraltooth is large and triangular on a Ijroad base, the lateral isrepresented only liy a tliin oblong plate, and the uncini areal)sent. In some species of Jcffreysia the uncini are said to beabsent, while present in others. Lamellaria has lost l)oth itsuncini, l)ut the radula of the allied Velutina is quite typical. Apeculiar feature in this group is the tendency of the nuirginalsto increase in number. A stage in this direction is perhaps seen 224 RADULA OF THE TAENIOGLOSSA in Ovnla, Pedicularia, and the Cyclostomatidar. Here the outer-most of the two marginals is by far the larger and broader, andis strongly pectinated on its upper edge ; in the Cyclostomatidae
Size: 2450px × 1020px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
