Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 Ch. XXY.] LOWER CARBONIFEROUS STRATA. 521 position of the siphuncle, however, clearly distinguishes the Goniatite from the Nautilus, and proves it to have belonged to the family of the Ammonites, from which, indeed, some authors do not believe it to be generically distinct. Fossil Fish.—The distribution of these is singularly partial; so much so, that M. de Koninck of Liege, the eminent palaeontologist, once stated
Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 Ch. XXY.] LOWER CARBONIFEROUS STRATA. 521 position of the siphuncle, however, clearly distinguishes the Goniatite from the Nautilus, and proves it to have belonged to the family of the Ammonites, from which, indeed, some authors do not believe it to be generically distinct. Fossil Fish.—The distribution of these is singularly partial; so much so, that M. de Koninck of Liege, the eminent palaeontologist, once stated to me that, in making his extensive collection of the fos- sils of the Mountain Limestone of Belgium, he had found no more than four or five examples of the bones or teeth of fishes. Judging from Belgian data, he might have concluded that this class of verte- brata was of extreme rarity in the carboniferous seas; whereas the investigation of other countries has led to quite a different result. Thus, near Clifton, on the Avon, there is a celebrated ' bone-bed,' almost entirely made up of ichthyolites; and the same may be said of the ' fish-beds ' of Armagh, in Ireland. They consist chiefly of the teeth of fishes of the Placoicl order, nearly all of them rolled as if drifted from a distance. Some teeth are sharp and pointed, as in ordinary sharks, of which the genus Cladodus affords an illustration ; but the majority, as in Psammodus and CocJiliodus, are, like the teeth of the Cestracion of Port Jackson (see above, fig. 322, p. 330), mas- sive palatal teeth fitted for grinding. (See figs. 581, 582.) Fig. 581. Fig. 5S2. Psammodus porosus, Agass. Bone-bed, Moun tain Limestone. Bristol; Armagh. CocMiodus contortus, Agass. Bone- bed, Mountain Limestone. Bris- tol; Armagh. There are upwards of seventy other species of fossil fish known in the Mountain Limestone of the British Islands. The defensive fin- bones of these creatures are not unfrequent at Armagh and Bristol; those know
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