. The Cambridge natural history. Zoology. 478 FISHES thys (Carboniferous and Lower Permian of Europe and North America). Fam. 2. Rhizodontidae.—Scales cycloid and overlapping. Paired fins obtusely lobate. Tail heterocercal, sometimes appar- ently gephyrocercal. Teeth with the external enamelled layer of dentine infolded towards the axis in the form of radially. Fig. 274.—Skull of a Rhizodont (RMzodopsis satiroides), Lower Carboniferous. A, lateral view ; B, the dorsal surface ; and C, ventral view. an. Angular ; d, dentary ; /, frontal ; , infra-dentary ; j, principal jugular plates ; ,
. The Cambridge natural history. Zoology. 478 FISHES thys (Carboniferous and Lower Permian of Europe and North America). Fam. 2. Rhizodontidae.—Scales cycloid and overlapping. Paired fins obtusely lobate. Tail heterocercal, sometimes appar- ently gephyrocercal. Teeth with the external enamelled layer of dentine infolded towards the axis in the form of radially. Fig. 274.—Skull of a Rhizodont (RMzodopsis satiroides), Lower Carboniferous. A, lateral view ; B, the dorsal surface ; and C, ventral view. an. Angular ; d, dentary ; /, frontal ; , infra-dentary ; j, principal jugular plates ; , lateral jugulars ; m, mandible ; , median jugular ; mx, maxilla ; o, orbit ; op, oper- culum ; p, parietal ; , post-frontal ; p,mx, premaxilla ; , preoperculum ; so, suborbital ; s. op. suboperculum ; sq, squamosal ; st, supra-temporal ; x, x, cheek plates. (After Traquair.) arranged folds. In some genera ring-like vertebral centra have been recognised and also a preoperculum. Genera:— Rhizodus, Lower Carboniferous of Scotland and Northumberland; TristicJiopterus^ (Fig. 275), Old Eed Sandstone of Scotland; Uusthenopteron^ (Fig. 276), Upper Devonian of Scaumenac ' Traquair, Trans. Roy. Soc. Edinb. xxvii. 1875, p. 383. ^ Whiteaves, Trans. Eoy. Soc. Canada, vi. 1888, p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
