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Explan ATION of PLATE 27. 43

Fig. S. a. Tube on the under surface of a scale for the passage of the mucous duct. See V. I. Note, p. 150. (Agassiz.) Fig. 9. Anterior extremity of the lower jaw of Holoptychus Hibberti, from the Limestone of Burdie house, near Edinburgh. See Note, V. I. p. 209. The rugged surface of this bone is very remarkable. (Hibbert.) Fig. 9". Small teeth of Holoptychus Hibberti, fluted externally towards their base, and having a hollow cone within. (Hibbert.) Fig. 9". A small tooth magnified. (Hibbert.) Fig. 10. One of the larger teeth in the Jaw of Holoptychus Hibberti, deeply fluted at the base, and having a hollow cone within. None of these teeth have sockets, but they adhere by a bony attachment to the jaw. (Hibbert.) ig. 11. Tooth of Holoptychus Hibberti. (Hibbert.) ig. 12. Tooth of Megalichthys Hibberti.” (Hibbert.) igs. 13, 14. Teeth of Holoptychus Hibberti. (Hibbert.) Figs. 11. 12. 13. 14. are from Burdie house.

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* Since the discovery of Megalichthys, which we have quoted in V. I. p. 210, Mr. W. Anstice, of Madeley, has found two jaws and punctate scales of the same species, in nodules of Iron stone from the Coal field of Coalbrook Dale; he has also found Ichthyodorulites, bones of fishes, and Coprolites, forming the nuclei of other balls of the same Iron stone.

Mr. Murchison has still more recently (1835) discovered remains of the Megalichthys, Holoptychus, and Coprolites, with several species of Unio, in the Wolverhampton Coal field. These great Sauroid fishes, which were first recognised at Edinburgh, in Sept. 1834, have also been detected in the English Coal fields of Newcastle on Tyne, Leeds, and Newcastle under Lyne.

Plate 27°. V. I. p. 212.

Fig. 1. Lepidosteus osseus, or bony Pike of North America. (Agassiz. Vol 2. Tab. A.) Fig. 2. Portion of the lower Jaw of Lipidosteus osseus, showing the occurrence of a row of larger conical hollow teeth, fluted externally, between two rows of smaller Teeth. (Original.) 2. a. Longitudinal section of a large Tooth, showing the internal hollow cone. (Original.) 2. b. Transverse section of a large Tooth. (Original.) Fig. 3. Transverse section of the Jaw. fig. 2. (Original.) Fig. 4. Fragment of a small upper Jaw of Megalichthys Hibberti, from Burdie house, showing a disposition of large and small teeth, similar to that in fig. 2. (Hibbert.) 4. a. b. Transverse section of the larger teeth. 4. c. Longitudinal section of a large Tooth." 4. d. Punctate scale of Megalichthys. Fig. 5. Aspidohrynchus: a fossil Sauroid fish from the Limestone of Solenhofen. (Agassiz, Vol I. Tab. F.)

PLATE 27°. V. I. p. 212.

Amblypterus: one of the fossil fishes peculiar to the Carboniferous strata. Agassiz, Vol. I. Tab. A. fig. 3.)

* It appears that in the Megalichthys and Holoptychus the structure of the teeth, both large and small, was precisely the same as in the large and small teeth of Lepidosteus osseus, both as to the hollow internal conical cavity, and the external flutings towards the base, and also as to their mode of growth by ascent of fibrous matter from the bony substance of the jaw, and not from roots placed in deep alveoli, as in many of the Saurians.

Explan ATION of PLATEs 27°. 27". 45

PLATE 27°. Vol I. p. 214.

Fig. 1. Fossil fish of the genus Microdon, in the family Pycnodonts. (Agassiz, Vol. I. Tab. G. fig. 3.)

Fig. 2. Os Vomer of Gyrodus umbilicatus, from the Great Oolite of Durrheim, in Baden. (Agassiz.)

Fig. 3. Os Vomer of Pycnodus trigonus, from Stonesfield, Oxon. (Original.) o

PLATE 27". V. I. p. 21S, Note.

A. Teeth of a recent Shark, allied to fossil species. Fig. 1. Anterior and Palatal Teeth of the Port Jackson Shark, (Cestracion Phillippi) (Phillip.) Fig. 2. Anterior cutting teeth of Port Jackson Shark, in the College of Surgeons, London. (Owen.) Fig. 3. Flat tessellated tooth of the same. Nat. size. a. Outer articular facet, showing the tubular structure of the bony base. b. Punctate surface of the superficial enamel. (Owen.) Fig. 4. Mesial, and inner articular facet of another large tooth of the same. a. Upper concave margin thinly covered with enamel. b. Lower bony margin without enamel. a'. b'. Bony base of the tooth exposed by removal of the Enamel. The surface is areolar, from the bending and blending together of the bony tubes. c. c'. Fractured edge of the marginal and superficial enamel. (Owen.) Fig. 5. Another anterior cutting tooth. a. Smooth enamelled point. b. Minutely rugous and tuberculated base. In some of the cutting teeth both sides of the base are rugous. (Owen.) B. Various forms of fossil Teeth, in the three sub-families of Sharks. (B. 1. to B. 13. Agassiz.) Figs. 1–5. Teeth of fossil Sharks in the sub-family of Cestracionts. See V. I. p. 218.

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uble row of similar hooks occurs on the first ray of the Barbel, (Barbus Vulgaris.) And anterior ray both of the dorsal and anal fins Carp, (Cyprinus Carpio.) ansverse Section of fig. 3, at a.” (De la Beche.)

PLATE 27°. V. I. p. 220.

rtion of the palatal teeth of Acrodus nobilis, mbling a cluster of contracted Leeches. These ‘h are in their natural place, adhering to the rved granular bone of the palate, which is well served, and impregnated with Carbonate of lime. Miss S. C. Burgon. Original.) !. Continuation of the three rows of teeth on the reverse of fig. 1. Scale one half. (Original.) 3. One of the largest teeth on the centre row, having the upper part of the Enamel worn away by friction. Nat. size. (Original.) 4. Magnified view of the minute tubercles of Enamel which grew upon the skin; the decay of the skin

the Lond. and Edin. Phil. Mag. Jan. 1836, the author has puba notice of his recent discovery of the jaws of four extinct of fossil fishes of the genus Chimaera, a genus hitherto unin a fossil state. The only known species (C. monstrosa) mates most nearly to the family of Sharks; and is found og Herrings and other migratory fishes. The Chimaera is one most remarkable among living fishes, as a link in the family of pterygians; and the discovery of a similar link, in the geoepochs of the Oolitic and Cretaceous formations, shows that uration of this curious genus has extended through a greater of geological epochs, than that of any other genus of fishes yet oned by Professor Agassiz, and leads to important considerations

ysiology. Ine Chimaera partakes of one remarkable character with the Cesno on. ereby this species alone, among living Sharks, is

ict forms of that family, in having the first ray into a strong bony spine armed with sharp ulite of the earliest fossil Sharks.

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