SUB-CLASS V 



GAXOIDEI 



65 



plates bear six ridges radiating outwards. The corresponding plates occurring 

 in the Trias, namely, in the bone beds of the Muschelkalk, Lettenkohle, and 

 Rhaetic, are distinguished by their larger size and a different number of ridges. 

 As a rule, the upper dental plates exhibit five, the lower ones only four 

 radiating ridges. The oldest known species (C. areriaceus, Quenst.) was 



Fig. 119. 



Ceraiodus forsUri, Krefft. Lateral aspect offish (A), base of skull (B), and mandible (C). Recent ; Queens- 

 land. Br, Branchial cavity ; c, Foremost rib ; d, Teeth ; na, Nasal openings ; PSph, Parasphenoid ; Ft, Pterygo- 

 palatine ; Qu, Quadrate ; Vo, Vomer (after Gunther). D, Ceratodus kaupi, Ag. Mandibular tooth on bony base, 

 1 /;; nat. size. Lettenkohle; Hoheneck, near Ludwigsburg. 



obtained from the Bunter Sandstone of Wurteinberg ; the latest, which are 

 the smallest, are discovered in Europe in the Bathonian of Stonesfield and 

 Northampton, England, in North America in the Upper Jurassic of Colorado. 

 Other examples occur in the Kota-Maleri beds of India, in the Karoo 

 Formation of South Africa, and in later deposits in Patagonia. A well- 

 preserved skull of C. sturi has been described by Teller from the Upper 

 Keuper of Polzberg, near Lunz, in Lower Austria. 



Sub-Class 5. GANOIDEL Agassiz. 1 Enamel-scaled Fishes. 



Trunk and tail usually covered with ganoid scales, rarely naked or with bony 

 plates. Skull covered with dermal bones, or completely ossified; pterygo-quadrate 

 arcade morally articulated with the cranium (hyostylic) ; gill clefts feebly separated, 

 opening into a cavity covered with a bony operculum. Vertebral column cartilaginous, 

 or with various degrees of ossification. Fin rays articulated, and fulcra usually 



1 Cope, E. B., Trans. Amer. Phil. Soc. vol. XIV. 1871, p. 445; and Amer. Nat. vols. XIX., 

 XX., XXL, XXIII. (1885-89).— Huxley, T. H., Preliminary Essay upon the Systematic Arrange- 

 ment of the Fishes of the Devonian Epoch (Mem. Geol. Snrv. dec. X.), 1861. — Kner, R., Betrach 

 tungen uber die Ganoiden als natiirliche Ordnung (Sitzungsb. k. Akad. Wiss. Wien, matn.-naturw. 

 CI. vol. LIV.), 1866. — Lutken, Chr., Ueber die Begrenzung und Eintheilnng der Ganoiden 

 (Palaeontogr. vol. XXII.), 1868. — Muller, Joh., Ueber den Bau und die Grenzen der Ganoiden 

 (Abhandl. k. Akad. Wiss. Berlin, 1834), 1836. — Traquair, R. 1_L. The Ganoid Fishes of the British 

 Carboniferous Formations. I. Palaeoniscidae (Palaeont. Soc), 1877, No. 2, 1901. — Vogt, ''.. Quelques 

 Observations qui servent a la Classiticatiou des Ganoides (Ann. Sci. Nat.. Zool. ser. 3, vol. IV. . 



VOL. II F 



