RHIZODONTIDiE. 
355 
The superficial film of ganoine upon the scales and external bones 
of this genus being very thin, it is usually destroyed. The scales, 
as a rule, exhibit a few concentric markings crossed by numerous 
very fine, radiating lines, due to the inner structural features. 
The osteology of the head and branchiostegal apparatus has been 
described in detail by Traquair x , who gives the restorations already 
described on p. 319 (fig. 47). 
Rhizodopsis saurpides (Williamson). 
1837. a Fossil Salmon,” W. C. Williamson, Phil. Mag. [3] vol. xi. p. 300, 
pi. ii. figs. 4-6. [Scales.] 
1841. Holoptychius, sp. nov., E. W. Binnev, Trans. Manchester Geol. 
Soc. vol. i. p. 165, pi. v. fig. 6. [Dentary bones ; E. W. Binney 
Collection.] 
1841. Holoptychius sauroides, E. W. Binney (errore), ibid. p. 165, pi. v. 
figs. 8, 10. [Scales.] 
1844. Holoptychius yranulatus , L. Agassiz, Poiss. Foss. vol. ii. pt. ii. 
p. 180 (name only). 
1849. Holoptychius sauroides, W. C. Williamson, Phil. Trans, p. 457, 
pi. xlii. figs. 21-23. 
1861. Rhizodus yranulatus, J. W. Salter, Foss. S. Welsh Coalfield 
(Mem. Geol. Surv.—Iron Ores Gt. Britain, pt. iii.), p. 223, pi. i. 
figs. 4-6 (also teeth, ibid, pi i. figs. 1-3, 7-9). 
1864. Holoptychius, sp. indet., Kirkby & Atthey, Trans* Tyneside Nat. 
Field Club, vol. vi. p. 235, pi. vi. fig. 4. 
1866. Rhizodopsis sauroides, J. Young, Quart. Journ. Geol. Soc. vol. xxii. 
p. 596, woodc. fig. 8. 
1867. Dittodusparallelus, B. Owen, Trans. Odontol. Soc. vol. v. p.325 
pi. i. [Micro, section of jaw; British Museum.] 
1867. Gcinolodus craygesii, R. Owen, ibid. p. 356, woodcut. [Dentary 
bone ; British Museum.] 
1867. Characodus confertus , R. Owen, ibid. p. 366, pi. xiii. [Micro, 
section of tooth.] 
1867. Gastrodusprcepositus, R. Owen, ibid. p. 370, pis. xiv., xv. [Micro, 
section of jaw ; British Museum.] 
1868. Rhizodopsis sauroides , Hancock & Atthey, Ann. Mag. Nat. Hist. 
[4] vol. i. p. 349. 
1870. Rhizodopsis sauroides, Hancock & Atthey, Nat. Hist. Trans. 
Northumb. & Durham, vol. iii. pp. 85, 91. 
1873. Orthognathus reticulosus, T. P. Barkas, Coal-Meas. Paleeont. 
p. 38, figs. 143,144. [Portions of jaws; T. P. Barkas Collection.] 
1873. Rhizodopsis, T. P. Barkas, ibid. p. 23, figs. 59-69. 
1875. Rhizodopsis sauroides, J. Ward, [Proc.] N. Staffs. Nat. Field Club 
p. 231. 
Trans. Roy. Soc. Edinb. vol. xxx. (1881), p. 169, woodcuts figs. 1-3 
2a 2 
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