342 
CROSSOPTERYGII. 
Genus RHIZiODUS, Owen. 
V 
[Odontography, 1840, p. 75.] 
Syn. Megalichthys, L. Agassiz & S. Hibbert, Trans. Roy. Soc. 
Edinb. vol. viii. 1836, p. 202 (non Megalichthys, L. Agassiz, 
1844 : see p. 378). 
The typical genus, imperfectly known, comprising species of very 
large size. Infraclavicle with a long, slender, upwardly-directed 
process. External bones and scales superficially ornamented with 
tubercles, ridges, or reticulations of ganoine. Crown of teeth 
smooth, compressed to a sharp edge anteriorly and posteriorly. 
No ossified vertebrae. 
So far as known, the genus Rhizodus is confined to the Lower 
Carboniferous, and its remains are very fragmentary. Of the fins, 
only the lobate pectoral has been discovered l . 
Rhizodus hibberti (Agassiz & Hibbert). 
[Plate XII. figs. 1-4.] 
1793. “ Fishes’ Teeth,” I). Ure, Hist. Rutherglen & Kilbride, p. 330, 
pi. xix. figs. 4, 6. 
1836. Megalichthys hibberti, Agassiz & Hibbert, Trans. Roy. Soc. 
Edinb. vol. xiii. p. 202, pi. viii. fig. 1 {non fig. 2), pi. ix. figs. 2, 3, 
9, 10; woodc. on p. 183. 
1837. Megalichthys hibberti, "YV. Buckland, Geol. & Mineral, ed. 2 
vol. ii. p. 43, pi. xxvii. fig. 12. 
1837. Holoptychus hibberti, W. Buckland, ibid. p. 43, pi. xxvii. figs. 
9-11, 13, 14. 
1841. Rhizodus hibbertii, R. Owen, Odontogr. vol. i.p. 75, vol. ii. p. 12, 
pi. xxxv. fig. 2, pis. xxxvi., xxxvii. 
1844. Holoptychius hibberti, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. p. 180 
(name only 7 ). 
(P) 1843. Phyllolepis tenuissimus, L. Agassiz, ibid. p. 180 (name only). 
1855. Rhizodus hibberti, E. M‘Coy, Brit. Pakeoz. Foss. p. 612. 
1855. Rhizodus gracilis, F. M‘Coy, ibid. p. 611, pi. iii. g-. fig. 17. 
[Dentary; Woodwardian Museum, Cambridge.] 
1865. Rhizodus hibberti, J. Young, Trans. Geol. Soc. Glasgow, vol. ii. 
p. 38. 
1866. Rhizodus, J. Young, Quart. Journ. Geol. Soc. vol. xxii. p. 599 
(except scales). 
1876. Rhizodus, W. J. Barkas, Monthly Review Dental Surgery, vol. iv. 
p. 394, figs, lxxx., lxxxi. 
1 R. H. Traquair, Ann. Mag Kat. Hist, [4] vol. xv. 1875, p. 267. 
