﻿ORTEOLEPTD.-K. 373 



Osteolepis nana, E. von Eichwald, Bull. Soc. Imp, Nat. Moscou, 

 vol. xvii. (1844), p. 831, and ibid. vol. xix. (1846), pt. ii. 

 p. 308, and Leth. Bossica, vol. i. (1860), p. 1555, pi. lvii. 

 fig. 9 ; L. Agassiz, Poiss. Foss. V. G. B. (1845), p. 155 ; 

 C. H. Pander, Saurodipt., Dendrodont. &c. devon. Syst. 

 (I860), p. 7. — Devonian ; Marjina. [Mandibular ramus ; 

 University of St. Petersburg. Scales from L. Carboniferous 

 Limestone of Podmokloye, Govt. Toula, also doubtfully 

 ascribed to this species.] 



Osteolepis tscliershyi, J. V. Bohon, Mem. Soc. Acad. Imp. Sci. St. 

 Petersbourg, [7] vol. xxxvi. no. 13 (1889), p. 13, pi. ii. 

 figs. 32-35, 39, 41.— Devonian; Valley of Kisil-kul, 50 

 versts W. of Minusinsk, Govt, of Tomsk, Siberia. [Scales, 

 &c. ; Imperial Academy of Sciences, St. Petersburg.] 



Genus THURSIUS, Traquair. 

 [Geol. Mag. [3] vol. v. 1888, p. 516.] 



Head as in Osteolepis and Diplopterus. Dorsal fins opposed to 

 the pelvic pair and the anal fin, respectively. Tail strongly hetero- 

 cercal ; caudal fin obliquely truncated posteriorly. Scales smooth 

 and punctate. 



Thursius macrolepidotus (Sedgwick & Murchison). 



1829. Dipterus macrolepidotus, Sedgwick & Murchison, Trans. Geol. 



Soc. [2] vol. iii. p. 143, pi. xvi. fig. 2 (? figs. 4, 5). 

 1835. Dipterus macrolepidotus, L. Agassiz, Poiss. Foss. vol. ii. pt. i. 



p. 115, pi. ii. fig. 4. 

 1855. Diplopterax macrolepidotus, F. M'Coy, Brit. Palseoz. Foss. 



p. 587 (in part). 

 (?) 1860. Osteolepis, C. H. Pander, Saurodipt., Dendrodont. &c. devon. 



Syst. p. 9, pis. i.-iii. (in part). 

 1888. Thursius macrolepidotus, R. H. Traquair, Geol. Mag. [3] vol. v. 



p. 516. 



Type. Small fish ; Mus. Geological Society of London. 



The type species, attaining a maximum length of about 0*25. 

 Head with opercular apparatus occupying one-fifth of the total 

 length; jaws much elongated ; operculum deeper than broad, sub- 

 operculum smaller and broader than deep. Pelvic fins situated 

 about halfway between the hinder margiu of the operculum and 

 the extremity of the tail ; first dorsal fin much smaller than the 



