HOLOPTYCHIIDJE. 
325 
Holoptychius giganteus, Agassiz. 
1839. Holoptychius , R. I. Murchison, Silur. Syst. p. 600, pi. ii. bis. 
fig. 3. 
1845. Holoptychius yiyanteus , L. Agassiz, Poiss. Foss. V. G. R. pp. 73, 
140, pi. xxiv. figs. 3-10. 
1848. Holoptychius princeps, F. M‘Coy, Ann. Mag. Nat. Hist. [2] 
yoI. ii. p. 310. [Scale ; Woodwardian Museum, Cambridge.] 
1854. Holoptychius yiyanteus , R. I. Murchison, Siluria, pi. xxxvi. 
%• 11 . 
1855. Holoptychius yiyanteus , F. M‘Coy, Brit. Palseoz. Foss. p. 594. 
1855. Holoptychius princeps, F. M‘Coy, ibid. p. 595. 
1888. Holoptychius yiyanteus , M. Lohest, Ann. Soc. Geol. Belg. 
vol. xv. p. 146, pi. vi. figs. 2, 3, pi. vii. figs. 5, 6. 
(P) 1889. Holoptychius yiyanteus ?, J. S. Newberry, Palseoz. Fishes 
N. America, p. 101, pi. xix. figs. 15, 16. 
1890. Holoptychius yiyanteus , Woodward & Sherborn, Cat. Brit. Foss. 
Vertebrata, p. 96. 
Type. Detached scales. 
A species of very large size, known only by detached scales. 
Scales of abdominal region externally ornamented with close, thick, 
irregularly tortuous, longitudinal ridges, often branching and 
interrupted, more or less replaced posteriorly by rounded tubercles ; 
caudal scales resembling those of H. nobilissimus. 
The variety of scale named H. princeps by M‘Coy is very rare, 
and may be regarded as exhibiting merely an extreme modification 
of the ornament just described. 
The teeth of this species are probably described as Denclrodus 
biporcatus (p. 338). 
Form, df Log. Upper Old Red Sandstone : Elgin and Nairn. 
Upper Devonian : Belgium and N.W. Russia. (?) Catskill Group : 
Pennsylvania. 
28869. Small (? caudal) scale; Scat Craig, near Elgin. 
Purchased, 1854. 
35992-93. About ten imperfect scales; Scat Craig. 
Purchased, 1861. 
P. 702. Six scales; Scat Craig. Egertoii Coll. 
P. 5094. Five imperfect scales ; Scat Craig. 
Presented by John Edward Lee, Esq., 1885. 
28868. Impressions of seven scales, one small example ornamented 
as “ H. princeps ” and traversed by a sensory canal; 
Alves, near Elgin. Purchased, 1854. 
