EXPLANATION OF PLATES 31
53
the siphuncle is laid bare at a. b. c. d. At e, e, and from thence inwards, it is covered by a soft calcareous coating or sheath.
y. y. Collar, projecting inwards from the transverse plates, and supporting the Siphuncle. See Note, V. I. p. 243.
Fig. 2. Upper horny mandible of the animal, with a hard calcareous point. (Owen.)
Fig. 3. Lower horny mandible, armed with a similar calcareous point. (Owen.)
Fig. 4. Calcareous point, and palate of upper mandible separated from the horny portion. (Owen.)
Fig. 5. Under surface, or palate of a Rhyncholite, or fossil beak, from the Lias at Lyme Regis, analogous to the recent specimen, fig. 4. (Original.)
Fig. 6. Upper view of another Rhyncholite from the same stratum and place. Black portions of the horny substance, in a state resembling charcoal, remain attached to its posterior surfaces. (Original.)
Fig. 7. Side view of the calcareous portion of an upper mandible, from the Muschel kalk of Luneville. (Original.)
Fig. 8. Upper view of another Rhyncholite from Luneville. (Original.)
Fig. 9. Palatal view of fig. 8. (Original.)
Fig. 10. Calcareous point of an under mandible from Luneville. The denotations on its margin resemble those on the recent mandible, fig. 3, and co-operating with the denotations on the Margin of the upper mandible, fig. 9, must have formed an Instrument (like the recent beak, figs. 2 and 3,) well fitted for the rapid demolition of Crustacea and small Shells. (Original.)
Fig. 11. Under surface of fig. 10.; it is strengthened by
