[070]

All the figures in this Plate are of nat. size.

Fig. l. Anterior Sheath and Ink-bag of Belemno-sepia, discovered by Miss Anning in 1828 in the lias of Lyme Regis, and noticed by Dr. Bucklancl (Lond. and Edin. Phil. Mag. May, 1829, P. 388,) as "derived from some unknown Cephalopod, nearly allied in its internal structure to the inhabitant of the Belemnite." This sheath is, for the most part, nacreous; in some places (d. d.) it retains the condition of horn. The corrugations on its surface indicate the lines of growth. At f. a transverse fracture shews the neck of the ink-bag. (Original.)

Fig. 2. The lower part of Fig. l. seen from another side; [071] the circular lines on the surface of its horny mem brane d, are lines of growth. (Original.)

Fig. 3. Belemno-sepia from the Lias at Lyme, in the Oxford Museum; the Ink-bag is preserved entire within the anterior conical sheath e. e. e.; the greater part of this sheath is highly nacreous, in a few places (d.) it is horny. (Original.)

Fig. 4. Large Ink-bag from the Lias at Lyme, in the collection of Mrs. Murchison, bearing on its surface undulating lines of growth similar to those on the surface of Fig. l. The Ink is exposed at c. c.; in other parts it is surrounded by the sheath, e. e. e. Nearly one-half of this sheath retains the appearance of horn, whilst the other half is highly nacreous. This interchange of condition, from horn to brilliant nacre, occurs in almost every specimen from the Lias at Lyme, in which the Ink-bag is accompanied only by the flexible anterior sheath, and the calcareous sheath has perished. (Original.)

Figs. 5. 6. 7. 8. Ink bags from the Lias at Lyme, partially surrounded by brilliant nacre. In no one of the specimens represented in Pl. 44" is the least trace of the calcareous sheath of the Belemnite preserved. See V. I. p. 376, Note. (Original.)