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careous partitions is least near the margin of the lamellæ. See Fig. 6'. (Original.)

Fig. 6"". Columnar appearance of the sinuous partitions when viewed laterally. (Original.)

Fig. 7. Unique specimen of Belemnites ovalis, from the Lias at Lyme Regis, in the collection of Miss Philpotts. A fracture at b, shows the chambered areolæ of the Alveolus. At e. the thin conical anterior horny sheath originates in the edge of the calcareous sheath, and extends to e". The surface of this anterior sheath exhibits wavy transverse lines of growth; it is much decomposed, slightly nacreous, and flattened by pressure.

Within this anterior conical sheath the Ink-bag is seen at c. somewhat decomposed, and partially altered to a dark gray colour. (Original.)

Fig. 8. Portion of the Ink-bag broken off from Fig. 7. c. and covered by that portion of the horny case which lay above it. The transverse lines e. on this portion, are the continuation of the lines of growth on the horny sheath of Fig. 7. e. e'. e". (Original.) Fig. 9. Belemnites Pistilliformis? from the Lias at Lyme, in the collection of Miss Philpotts, having a portion of its ink-bag at c. (Original.)

Figs. 10. 11. 12. Belemnites from the Jura limestone of Solenhofen, figured by Count Munster in Boué's Mémoires Géologiques, Vol. I. Pl. 4. In 10 and 12 the form of the anterior horny sheath is preserved, to a length equal to that of the calcareous shaft of the Belemnite, but in none of them is the Ink-bag visible.* (Munster.)

* Von Meyer mentions (Palæologica, P. 322, 1st. Edit. 1832,) that he has seen an Ink-bag at the upper end of a Belemnite from the Lias of Banz, and asks, "Do Belemnites possess an Ink-bag like that of the Sepia ?"

Fig. 13. Chambered alveolar cone and horny sheath of a large Belemnite from the limestone of Solenhofen ; the calcareous sheath or Belemnite itself has disappeared. (Munster.)

(Ori

Fig. 14. Belemnites brevis? from the Liás at Lyme; Nat. size. The length of the shaft of this Belemnite does not exceed that of the Beloptera (Fig. 15;) a small fragment only of its alveolus is preserved, but the place it occupied is filled with calcareous spar, and the hollow cone above it with lias. ginal.) Fig. 15. Beloptera. In this fossil we have an intermediate link between the Belemnite and the shell or sheath of Sepia officinalis. a. represents the apex of the sheath, e. e. its posterior expansion, analogous to that at Fig. 4. e. e. and at Fig. 4'. e'; e' is its anterior expansion, bearing on its internal surface annular marks derived from the transverse septa of the alveolus. (Blainville.)

PLATE 44". V. I. p. 282. Note.

All the figures in this Plate are of nat. size. Fig. 1. Anterior sheath and Ink-bag of Belemno-sepia discovered by Miss Anning in 1828 in the Lias of Lyme Regis, and noticed by Dr. Buckland (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 shows the neck of the ink-bag. (Original.)

Fig. 2. The lower part of Fig. 1. seen from another side;

the circular lines on the surface of its horny membrane 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. 1. 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. 283, Note. (Original.)

PLATE 45.* V. I. p. 296 et seq.

Fig. 1. Limulus Americanus (Leach,) a young specimen from Honduras, one-third of nat. size. b'. Right compound Eye magnified. ". Two single

* The following letters are applied in Pl. 45 and Pl. 46, to corresponding parts of different animals. a. the shield; a. lateral portion of the shield; b. the eye; b'. eye magnified; U'. frontal eyes; c. the back; d. the tail; e. branchiæ.

Eyes in front of the shield. See V. I. p. 297. (Original.)

Fig. 2. View of the under surface of Fig. 1, showing the crustaceous legs beneath the shield (a,) and the

swimming feet bearing the Branchiæ (e,) beneath the body (c.) Scale, one-seventh of nat. size. Fig. 2. e. Swimming feet, (see Fig. 2 e,) enlarged to the scale of Fig. 1.

Fig. 2. e". Posterior surface of one of the swimming feet, bearing the fibres of the Branchiæ. (Original.) Fig. 3. Front view of magnified figure of Branchipus stagnalis. 3. b. The left eye mounted on a peduncle. 3. b'. The right eye still more magnified. (Original.) Fig. 4. Side view of Branchipus stagnalis, nat. size. Fig. 5. Magnified view of the back of Branchipus stagnalis. See V. I. p. 298. (Original.)

Fig. 6. View of the back of a Serolis from Senegal, given by M. Dufresne to Dr. Leach. See V. I. p. 296. (Original.)

Fig. 7. View of the under surface of Fig. 6, showing the union of crustaceous legs with the membranous branchiæ, e.* (Original.)

Fig. 8. Magnified view of the Branchiæ at Fig. 7, e. Fig. 9. Back of Asaphus caudatus, from Dudley, in the collection of Mr. Stokes. (Original.)

Fig. 10. Side view of the left Eye of Fig. 9, is magnified. Fig. 10'. Another Eye of Asaphus caudatus, in the col

lection of Mr. Bright, from the W. side of Malvern Hill. In the front of this fossil are circular depressions on the stone, from which the petrified lenses have fallen out; on each side, the lenses remain in their natural place. (Original.)

* Figs. 3, 5, 6 and 7, are from original drawings by Mr. Curtis in the collection of Mr. C. Stokes.

Fig. 11. Anterior segment of the left Eye of Fig. 9, still more highly magnified, to show the circular lenses set in their respective margins, each surrounded by six minute tubercles. (Original.)

Fig. 11'. Magnified view of a portion of the eye of Calymene macrophthalmus. (Hoeninghaus.)

Fig. 12. Under surface of the anterior portion of the

shield of Asaphus platycephalus, from Lake Huron. A unique specimen, showing at f. an entrance to the stomach, analogous to that in recent Crabs. See Geol. Trans. N. S. Vol. i. Pl. 27. (Stokes.)

PLATE 46. V. I. p. 294 et seq.

Figs. 1. 2. 3. Calymene Blumenbachii, from the Transition Limestone of Dudley. a. The shield covering the head. a'. Lateral portion of the shield, separated by a suture from a.; the central part of this suture forms the lateral Margin, or Rim of the cavity of the Eye. This Margin is composed of two parts, united to receive the Lens, like the rims that enclose the edges of the glasses, in a pair of Spectacles. The Lens has usually fallen out from the Eyes of fossils of this species, as often happens after death in the Eyes of the recent Grapsus pictus, and also in the common Lobster. b. The Eye. C. The dorsal portion, composed of articulating plates, that move on one another like the plates of a Lobster's tail. d. The tail.

Fig. 1. Side view of the animal rolled up like an Oniscus. (Scharf.)

Fig. 2. View of the back of the Animal expanded for swimming; the Tail d, is composed of plates that had no movable articulations. (Original.) Fig. 3. Front view of the same animal rolled up; the

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