﻿HOLOPTYCHIIDiK. 323 



wrinkles, occasionally replaced by tubercles. Head depressed, the 

 bones superficially granulated ; teeth compressed, with a pair of 

 sharp edges at least in the upper portion ; anterior median jugular 

 plate absent. Pelvic fins obtusely lobate, situated at or behind 

 the middle of the body ; first dorsal fin opposite the pelvic pair, 

 second dorsal opposite or partly posterior to the anal ; tail hetero- 

 cercal, the upper lobe of the caudal fin small, the lower lobe 

 triangular and obliquely truncated. 



I. Holoptychius proper. 

 Holoptychius nobilissimus, Agassiz. 



1835. Gyrolepis giyanteus, L. Agassiz, Poiss. Foss. vol. ii. pt. i. p. 175, 



pi. xix. fig. 13. 

 1839. Holoptychus nobilissimus, L. Agassiz, in Murchison's Silur. Syst. 



p. 600, pi. ii. bis. tigs. 1, 2 (specitic name giganteus withdrawn). 

 1841. Holoptychius nobilissimus, H. Miller, Old Red Sandst. p. 162, 



pi. ix. fig. 2. 



1844. Holoptychius murchisoni, L. Agassiz, Poiss. Foss. V. G. R. p. 72, 

 pi. xxii. fig. 2. [Scales.] 



1845. Holoptychius nobilissimus, L. Agassiz, ibid. pp. 73, 140, pi. xxiii., 

 pi. xxiv. fig. 2, (?) pi. xxxi. a. fig. 26. 



1855. Holoptychius nobilissimus (' ? amend to noblei '), F. M'Coy, Brit. 



Palaeoz. Foss. p. 595. 

 1860. Holoptychius nobilissimus, E. von Eichwald, Leth. Rossica, vol. i, 



p. 1572. 

 1888. Holoptychius nobilissimus, M. Lohest, Ann. Soc. Geol. Belg. 



vol. xv. pp. 127, 139. 

 1888. Holoptychius dewalquei, M. Lohest, ibid. p. 134, pi. i. fig. 5, 



pi. ii. figs. 1-4, pi. iii. figs. 1, 3, 5, 6, pi. v. figs. 1-3. [Scales; 



M. Lohest Collection, Liege.] 

 1890. Holoptychius nobilissimus, Woodward & Sherborn, Cat. Brit. 



Foss. Vertebrata, p. 97. 

 1890. Holoptychius nobilissimus, R. H. Traquair, Proc. Roy. Soc. 



Edinb. vol. xvii. p. 388. 



Type. Fish wanting caudal extremity, ventral aspect; British 

 Museum. 



The type species, of very large size. Head and opercular 

 apparatus occupying about one-fifth of the total length. Scales 

 externally ornamented with numerous large branching ridges, often 

 interrupted and partly tubercular on the ventral aspect of the 

 abdomen, continuous and more delicate on the caudal pedicle ; the 

 superficial ridges rarely alternating with, and continued by, series of 

 small tuberculations at the anterior edge of the exposed area of the 

 scale. 



y2 



