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nation, examples of the following genera, from this celebrated locality, viz.-Lates, Cyclopoma, Enoplosus, Serranus, Pelates, Myripristis, &c.

Of this Order, and from the same inexhaustible mine of Ichthyolites, are the fine specimens of Callipteryx recticaudus, and of the Sparoids (Breams), Cottoids (Bullheads), and Goboids; and that remarkable fish the Semiophorus velifer, in the Case before us.

Beneath the last-named Ichthyolite, there is a rare specimen of Fistularia magnifica, from the Engi slate of Glaris.

A beautiful example of Mugil (M. princeps), from Aix, in Provence, is placed in the upper part of the same case (No. 20); it was formerly in my collection; the muscles of the abdomen, fin-rays, &c. are finely preserved. Near these fishes there is a remarkable ichthyolite, Calomopleurus cylindricus, from the north of the Brazils, by Mr. Gardiner, from strata supposed to be of the cretaceous epoch.

CYCLOID ORDER.-The essential character of the fishes of this Order are an osseous skeleton, and scales of a circular or cycloid form, with smooth margins, composed of plates of horn or bone, without enamel. To this Order the greater number of the fresh-water fishes belong; as the Pike, Carp, Trout, Salmon, &c. The paleontological history of this Order corresponds with that of the Ctenoids; in fact, the fishes of these two divisions, appear to constitute but one natural group.

There are no known cycloid fishes in strata below the Cretaceous formation; and those which occur in the Chalk belong to extinct genera. In the ancient tertiary the cycloids abound. Monte Bolca has yielded some genera and many species, hitherto unknown elsewhere. The collection contains a great many beautiful examples of the various generic types; these are enumerated in the general list, and the position in the cabinets of the most important fossils is indicated by the table at the bottom of the page.1

ENCHODUS.-Wall-case C. (No. 21.)-The upper and lower jaws, with long, pointed, conical teeth, of a fish of the scomberoid or mackerel family, in high relief from the blocks of chalk to which they are attached, are placed on the middle shelf of this Case. These teeth are remarkably well developed; they are rounded on the inner aspect and compressed externally; the two anterior ones of the lower jaw are very

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large, and placed close to each other on each side the median line; the margins of the jaws are fringed with brush-teeth, and the jaws marked with granulated longitudinal ridges. These dental characters resemble those of two living genera of fishes, the Thyrsites and Lepidopus. The specimens are from Lewes, and were collected in 1820.1

SAURODON-Wall-case C. (No. 23.)-There are several detached, lanceolate, laterally compressed teeth, and two or three specimens in which teeth of the same character are affixed to a portion of the jaw, in the front of this division of Case C. The latter instructive specimens were in the cabinet of the late Mr. Dixon; the former are from my collection. These fossils belong to an extinct genus of fishes, which resembled the Sphyraena, or Barracuda Pike, in the form of the teeth and length of the jaws. The teeth on the palatine bones are barbed, and finely serrated.3 The teeth of these fishes were first discovered in the Cretaceous Greensand of New Jersey, in the United States.1

HYPSODON (H. Lewesiensis).- Wall-case C. (No. 24.)—The ichthyolites thus named are also from the Lewes chalk, and were among my earliest discoveries. They consist of the teeth and jaws, vertebræ, and some of the cranial bones, of a very large predaceous fish, whose long, conical, unequal teeth, remind us of the sauroids of the ganoid order. The three pieces of chalk containing portions of jaws with teeth, vertebræ, &c. are fragments of a large block, which was broken up by the quarrymen before the animal remains were observed. I collected the least injured pieces, and removed the chalk so as to expose the bones now apparent. This genus is now referred to the family of Scomberoesocids, of Müller.

Of the freshwater fishes the Cyprinoids or Carps, there are fossil species of Tinca or Tench (T. furcata, and T. leptosoma) from Eningen; and of the Leuciscus or Luce, there is a very large fossil species (L. Hartmanni) from the tertiary strata of Steinheim, in Wirtemberg, and a small fish of the same genus (L. papyraceus), from the paper-coal of Bayreuth.

The fossil Esocids or Pikes, are in Cases Nos. 24 to 27, and comprise some beautiful examples of Esox lepidotus from Eningen. Of an extinct fresh-water genus named Sphenolepis, allied to the Pikes, there is a specimen of a very large species with robust vertebræ, and long striated scales, (S. squammoseus,) from Aix; and the S. Cuvieri from Montmartre. The Ichthyolites of the Halecoids or Herring family, comprising the Clupea and Salmonidæ, are placed in Cases No. 25 and 26. Among the former is the Clupea Scheuchzeri, from the slate of Glaris.

1 Figured in "Fossils of the South Downs," under the name of Esox Lewesiensis, Tab. XLI. "Geology of the South-East of England," p. 140. 2 Figured in "Fossils of the South Downs," Tab. XXXIII. 3 See "Medals of Creation," p. 666, Lign. 136, fig. 3.

4 See "Medals of Creation," p. 669.

5 Tab. XLII. "Fossils of the South Downs," represents a vertebra, teeth, and bones of a fish of this genus.

6 These specimens are figured in M. Agassiz's "Recherches sur les Poissons Fossiles."

LIGN. 92. OSMEROIDES MANTELLI; A FISH OF THE SALMON TRIBE, FROM THE LOWER CHALK, LEWES, 1821.

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OSMEROIDES.-Wall-case D.1 (No. 26).-The fossil fishes of the Salmon family, from the Sussex chalk, deposited in this Case, were the most beautiful ichthyolites in my collection; and though since the exposure of the specimens to the atmosphere of London they have lost much of their original brightness, and the pure white chalk appears like chalkmarl, yet the uncompressed state of many of these fishes, and the high relief in which they appear, render them objects of interest even to the uninstructed observer. These Ichthyolites are nearly related to the common Smelt (Osmerus); whence the name given to the genus, Osmeroides, by M. Agassiz. They were discovered, figured, and described, in my "Fossils of the South Downs," under the name of Salmo Lewesiensis. There are three species, two of which are well marked, viz, O. Mantelli, and O. Lewesiensis. The former has a short subcylindrical body, and seldom exceeds nine inches in length; the latter is of an elongated form, and sometimes attains a length of fourteen inches; the dorsal fin has more rays than in the former.

The first species is generally found with the head and body uncom pressed; the most remarkable specimen hitherto discovered is on the front ledge of No. 26, and is figured in Lign. 92. This matchless ichthyolite is nine inches long, and the chalk has been cleared away so as to expose the entire body, lying six inches in relief above the block, to which it is attached by the dorsal aspect. The mouth of the fish is open, the opercula or gill-covers, and the branchial arches are expanded; the pectoral and ventral fins, and the dorsal fin, are in their natural position; the five rays of the dorsal are erect: there are but few traces of the caudal fin; in a specimen of Osmeroides Lewesiensis, in the same Case, a little adipose process, as in the recent Salmons, is situated between the dorsal fin and the tail.2

ACROGNATHUS (A. boops).—Wall-case D. (No. 25.)- This is a small unique ichthyolite which I discovered in a block of chalk from Southerham. It is an abdominal cycloid fish, with a large and flat head, and enormous orbits. The form of the fish, when recent, is shown in Lign. 93.

AULOLEPIS (A. typus).-Near the last described fossil there is placed another unique fish from the same locality, which is characterised by its slender muzzle, and conical teeth. The figure of the original is given in Lign. 94.

ICHTHYOLITES OF RECENT SPECIES; MALLOTUS.-Wall-case D. (No. 27.)— The eminent naturalist to whose labours the Ichthyologist is so greatly

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indebted, affirms that of the many hundred fossil specimens submitted to his examination, only one can be identified with any living fish. The ichthyolites which form this remarkable exception are found in nodules of indurated clay, at the Sukkertop, on the West Coast of Greenland, and are identical with the living Mallotus villosus, or Angmarset, a

LIGN. 93.-ACROGNATHUS BOOPS. (nat. size.)

small fish allied to the Smelts, of which there is but one species, an inhabitant of the northern seas. These fossils are supposed to be of very recent formation; there is a specimen in the last division of Case D.1

1 See "Recherches sur les Poissons Fossiles," tome v. Pl. LX. for figures of the skeleton of the recent Mallotus, and the fossil remains.

LIGN. 94.-AULO LEPIS TYPUS. (Length six inches.) UNIQUE ICHTHYOLITES, FROM THE CHALK. LEWES. (Discovered by the Author.)

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