MANUAL OF NATURAL HISTOEY. 555 



formation, and valuable building-stones and marbles 

 are likewise afforded. 



Among the organic remains of tlie Carboniferous 

 group, we may observe three species of the curious 

 reptile, Archegosaurus, with the body of a toad 

 and the jaws and teeth of a lizard, and the skin 

 covered with long, narrow, tile-like, horny scales, 

 arranged in parallel rows ; foot-prints of other rep- 

 tiles have been also discovered in the coal strata of 

 the United States. The fishes comprehend Pleu- 

 racanthus, Hybodus, an extinct genus of Placoids, 

 allied to the Sharks, Amblypterus and Palceonis- 

 cus, heterocercal Lepidoids, and Megalichthys, and 

 Acrolepis, great heterocercal Sauroids, with large, 

 pointed, conical teeth, the arch-tyrants of the ancient 

 seas ; also the placoid Deplerus, with scaly armour, 

 and two dorsal, and two ventral, fins. The remains 

 of Annulose animals comprise the fossil King-crab 

 or Limulus, Nebalia, and Apus, with a few Tri- 

 lobites, and several Entomostraca, as Cypridella, 

 Gypridina, and Cyprella. Among Arachnidans, a 

 scorpion (Cyclopthalmus), from the coal formation, 

 near Prague, and among insects, Curculionidce, 

 several Orthoptera, including Cridites and Blatlina, 

 and the neuropterous genus, Corydalus, may be enu- 

 merated. The molluscous forms embrace the cepha- 

 lopodic, chambered shells of the straight, uncoiled 

 Ortlioceras, and the Goniatites, with the borders of 

 the septa simple ; while Euomphalus, divided into 

 chambers, but without siphuncle, and the fragile 

 Bellerophon, with Turbo, Trochus, Turritella, and 



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