﻿162 HETEROSIRACI. 



Pteraspis rostrata (Agassiz). 

 [Plate IX. fig. 1.] 



1835. Cephalaspis rostratus, 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. 

 1865. Pteraspis rostratus, E. R. Lankester, "Rep. Brit. Assoc. 1864, 



Trans. Sect. p. 58. 

 1868. Pteraspis rostratus, E. R. Lankester, Fishes Old Red Sandst. 



pt. i. (Pal. Soc), p. 32, pi. iv. figs. 1-3, 7, 8, pi. v. fig. 4, pi. vi. 



figs. 1-3, 6, 9, pi. vii. figs. 3, 5, 7, 9, 10, 12, 13, 19. 



Type. Dorsal shield ; olim Sir R. I. Murehison's 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 groove. 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 lloycli. 



Form. § Log. Lower Old Red Sandstone : Herefordshire, 

 Monmouthshire, and Glamorganshire. 



P. 4110-11. Tw T o very large imperfect specimens, partly 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. McCidlough, 1883. 



P. 5038. Smaller splintered example; Gethlellydd. 



Presented by John Edward Lee, Esq., 1885. 



P. 5034-37. Shield as large as Nos. 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. 



