162 
HETEROSIRACI. 
Pteraspis rostrata (Agassiz). 
0 . [Plate IX. fig. 1.1 
/ r y C ft / Lp^s-S-p^* s- 1 / .p^s/p^a. 
1835. Cephalaspis rostrcitus , L. Agassiz, Poiss. Foss. vol. ii. pt. i. p. 148. 
pi. i. b. figs. 6 , 7 . 
1861. Pteraspis rostratus , T. H. Huxley, Quart. Journ. Geol. Soc. 
vol. xvii. p. 165, woodc. 
I 860 . Pteraspis rostratus , E. R. Lankester, Rep. Brit. Assoc. 1864, 
Trans. Sect. p. 58. 
1868. Pteraspis rostratus, E. R. Lankester, Fishes Old Red Sands!, 
pt- i- (Pal. Soc.), p. 32, pk iv. figs. 1-3, 7, 8 , pi. v. fig. 4, pi. vL 
figs. 1-3, 6 , 9, pi. vii. figs. 3, 5, 7, 9, 10,12, 13, 19. 
Type. Dorsal shield; ahh^irAL^^ Collection.^^ 
Rostrum obtuse, its maximum width being three quarters as great 
as its length, and the superior aspect marked with a longitudinal, 
broad flattening or shallow grooye. Disc oblong, less than twice as 
long as broad, with parallel sides, very convex transversely, and 
tapering abruptly posteriorly; dorsal spine large; cornua abruptly 
truncated. 
This is the type species and is the largest known form, the dorsal 
shield sometimes attaining a total length of 0"14. The ventral shield 
is probably described as Scaphaspis lloydi. 
Form. Sf Loc. Lower Old Red Sandstone : Herefordshire* 
Monmouthshire, and Glamorganshire. , 
P. 4110-11. Tw t o very large imperfect specimens, parti}" in counter¬ 
part, displaying the orbits and the pineal pit, and probably 
not less than 0*14 in length when complete ; Great Skirrid 
Quarry and Gethlellydd, near Abergavenny. 
Presented by Dr. D. M. McCullough , 1883. 
P. 5038. Smaller splintered example; Gethlellydd. 
Presented by John Edward Lee y Esq., 1885. 
P. 5034-37. Shield as large as Xos. P. 4110-11, in counterpart, and 
three imperfect median discs of similar specimens ; Gold- 
tops, near Newport, Monmouthshire. The fourth specimen 
seems to show the natural form of the disc, extremely 
arched from side to side; its transverse section is given in 
the outline, PI. IX. fig. 1. 
Presented by John Edward Lee , Esq., 1885. 
P. 5373. Two imperfect smaller shields, one showing the ornamenta¬ 
tion of the rostral plate; Cradley, near Malvern. 
Purchased , 1887’ 
