Fig. 3. Lituite in the Transition lime-stone of Oeland. a. Siphuncle of Lituite. (Original.)

Fig. 4. Section of an Orthoceratite in the Transition limestone of Oeland, in the collection of C. Stokes, Esq. (Original.)

a. Siphuncle of the same.

Fig, 5. Baculite, from Chalk of the Cotentin; terminating at its large end in the chamber a. (Original.) • Fig. 5. b. Front view of the transverse plate of a Baculite, showing the margin to be disposed in lobes and saddles, and the place of the Siphuncle to be on the back of the shell at c. (Original.)

Fig. 6. Transverse section of a Nummulite. (Parkinson, V. 3. Pl. X. Fig. 16.)

Fig. 7. Longitudinal section of another Nummulite.* (Parkinson.)

one specimen the Eye is preserved, and is very large in proportion to the body. These Mollusks form the prey of the Physali, and were caught entangled in their Tentacula.

L'Echo du Monde Savant, 1 Mai, 1836.

* Among the microscopic fossil shells placed by D'Orbigny in the same Order as Nummulites (Foraminiféres), Count Munster enumerates 40 species from the Cretaceous free stone of Maestricht. Mr. Lonsdale also has discovered 16 species of microscropic foraminifers in the English Chalk. (See V. I. p. 337, Note.) Microscopic shells of this Order occur in countless myriads throughout the Tertiary strata. (See V. I. p. 290.)

The Sand of the Shores of the Adriatic, and many Islands in the Archipelago, is crowded with recent microscopic shells of the same kind.

It is mentioned in our Note, V. I. p. 288. that doubts have arisen as to the supposed origin of many of these minute multilocular shells from Cephalopods. Some recent observations of M. Dujardin have induced him to refer the Animals which construct the Miliola and some other microscopic foraminiferous shells, to a new Class of animals of a lower degree than the Radiata, and possessing a locomotive power by means of minute tentacular filaments. He proposes to give them the name of Rhizopodes. Ann. des Sci. Nat. Mai, 1835. p. 312.

Fig. 8. Hamites Bucklandi, (Phillips,) from the Gault or Speeton Clay, in the collection of Mr. I. Phillips, of York. (Original.)

Fig. 8a. Transverse septum of Fig. 8, showing the lobes and saddles, and the siphuncle at a.

Fig. 9. Hamites armatus, from the upper Green Sand, near Benson. (Sowerby.)

Fig. 10. Transverse section of the same, showing the siphuncle, on the back, between the spines.

Fig. 11. Hamites from Folkstone Clay, showing the spiral Ribs of the outer shell. At a. we see the Siphuncle, and the lobes and saddles of the transverse Plate. Fig. 12. Fragment of the cast of the interior of another Hamite from Folkstone Clay, showing the Siphuncle at a. The removal of the outer shell shows the sinuous edges of the transverse Plates beneath the Ribs. (Original.)

Fig. 13. Fragment of Hamites articulatus (Sow.) from the Green Sand at Earl Stoke, showing the Siphuncle (a.) covered by a small portion of the shell. The sinuous terminations of the transverse plates are visible beneath the ribs, having their secondary lobes rounded outwards (b.) and pointed inwards (c.) like the secondary lobes of Ammonites. (Original.)

Fig. 14. Fragment of Turrilites Bergeri, in the collection of G. B. Greenough, Esq. from the Green Sand formation. The siphuncle is seen near the upper or dorsal margin of two whorls at a. a.; the sinuous edges of the transverse plates are visible on the middle whorl; and the entire surface of a transverse plate is laid open at the smaller end of a third whorl, showing its lobes and saddles to be analogous to the same parts in Ammonites. (Original.)

Fig. 15. Scaphites Equalis, from Chalk near Rouen, in the collection of Mr. J. Sowerby; the sides of the external shell are strengthened and ornamented by ribs and tubercles; and the edges of the transverse plates disposed in sinuous foliations (c.) as in Ammonites. The mouth or outer margin (b.) returns so nearly into contact with the air chambers (c.,) that the want of space at this part for the expansion of arms and head, makes it probable that the Scaphite was placed entirely within the body of its animal. (Original.)

Fig. 16. Transverse section of the chambered portion of Fig. 15, showing the arrangement of the lobes and saddles to be similar to that of Ammonites; the siphuncle also is seen on the dorsal margin at a. (Original.)

Fig. 17. Longitudinal section of the calcareous Sheath and Alveolus of a Belemnite.

a. Alveolus, or internal shell, divided by transverse Septa into air chambers. See V. I. p. 281.

b. Siphuncle, passing along the margin of the air chambers.

c. Apex of the fibro-calcareous sheath, or solid Cone of the Belemnite.

PLATE 44'. V. I. p. 280, et seq.

Illustrations of the probable nature of the Animals that gave origin to Belemnites.*

* In the description of Pl. 44'. and Pl. 44". the following letters indicate the same parts in each specimen to which they are applied.

a. The Apex of the calcareous shell, or sheath.

b. Alveolar portion, or chambered shell.

c. Ink-bag.

d. Portions of the thin anterior horny sheath, sometimes highly

e. S

nacreous.

f. Neck of Ink-bag.

Fig. 1. Imaginary restoration of Belemnosepia, showing the probable place of its Ink-bag, and of the internal shell or Belemnite. The three component parts of this Belemnite are represented as if longitudinally bisected: the place assigned to this Ink-bag is nearly the same as in the recent Loligo. (Original.) Fig. 2. Sepia officinalis, showing the position of the internal shell or sheath (Sepiostaire) within the dorsal portion of its sac. Its apex (a,) and calcareous dorsal plates (e,) correspond with the apex calcareous conical sheath of a Belemnite.

Fig. 3. Sepia officinalis, laid open along the ventral portion of its Sac, to show the position of its Ink-bag. (Original.)

Figs. 3. a. 3. b. 3. c. Rhyncholites, found in contact with Belemnites in the Lias at Lyme Regis. Nat. size. (Original.)

Fig. 3. d. Beak of a small Testudo from Chalk, in the collection of Mr. Mantell, showing a fibro-cancellated bony structure, very different from the compact shelly condition of the Rhyncholite, for which it may from its size and shape be mistaken. (Original.)

Fig. 4. Ventral surface of a Sepiostaire; the elongated

shallow cone, or cup, (e. e. e'. e'.) is composed of very thin calcareous plates, alternating with horny membranes, which are expanded outwards to form the thin margin of the cone. This irregular cone or shell represents the hollow cone at the larger extremity of the Belemnite, (Fig. 7. b. b'. e. e'. e''.) which includes its Alveolus (b. b'.) and Ink-bag (c.) Within this shallow sub-conical shell of the Sepiostaire is contained its alveolus, or calcareous chambered portion, (Fig. 4. b.) which represents the

chambered alveolus in the Belemnite, (Fig. 7. b. b'.) but has no Siphon. (Blainville.)

Fig. 4. Longitudinal section of the apex of the shell of Sepia officinalis. This apex is composed of granular calcareous matter (a.), alternating with conical horny lamine, which expand laterally into the horny margin (e.) (Original.)

Fig. 5. Longitudinal view of Fig. 4. The apex (a.) represents the apex of a Belemnite. The back of the shell (e.) the dorsal part of a Belemnite; and the alveolar portion (b. b'.) represents the internal chambered shell of a Belemnite. (Blainville.)

Fig. 6. Anterior extremity of the lamellæ, or alveolar plates, exposed by a longitudinal section in Fig. 5. In the mature animal these lamellæ are nearly 100 in number; a few of them only are here represented.

These alveolar plates form the internal chambers of the Sepiostaire, and represent the transverse plates of the Alveolus in Belemnites, and other chambered shells; but as the Sepiostaire has no siphuncle, its chambers seem not subservient, like those of the Belemnite, to the purpose of varying the specific gravity of the animal; the intervals between its plates are occupied by an infinite number of thin winding partitions standing perpendicularly between the lamellæ.

Figs. 6'. 6". Thin calcareous partitions winding between, and supporting the alveolar plates of the Sepiostaire. The sinuous disposition of these partitions increases their efficacy in resisting pressure, on the same principle, as in the foliated edges of the transverse plates of Ammonites. The sinuosity of the cal

*

* Dr. Fleming has accurately described the structure of these partitions, as exhibiting perpendicular laminæ, waved and folded in brainlike gyrations which occasionally anastomose.