DESCRIPTION OF THE SPECIES OF PTERYGOTUS 243 
neck is shorter. From P. anxglicus, the shorter form, the short neck, 
blunt teeth, and convex upper lobe (a) overhanging the teeth, distin- 
guish it; but the sculpture raised into thick, prominent, boss-like 
plice is almost identical. The lower edge is tuberculate, and even 
spinous ; our figure does not show this part. <A little comparison of 
this specimen with Plate VII. [Plate 18] fig. 2, will show that both 
in the upper or front edge (a), and on the lower or hinder edge (0), 
the terminal lobe is more prominent in P. /udenszs. We do not know 
the other joints, unless Plate XII. [Plate 23] fig. 6, be the pen- 
ultimate one. It has exactly the form of that of P. gigas. 
Thoracic? Appendages? Plate XII. [Plate 23] figs. 4, 5.— 
The nature of these is not understood, nor do these specimens show 
the characteristic irregular base. But they differ specifically both 
from the similar appendages in P problematicus, Plate XII. [Plate 
23] fig. 16, and from the more perfect one figured in Plate XIII. 
{Plate 24] fig. 16, by their deep terminal notch. The outer edges 
are thickened, and the substance of the whole appendage is thick. 
The lateral plicee run down in oblique rows on the inner (?) surface, 
becoming more and more linear, till they become straight lines like 
the penne of a feather; and on the outer side, impressed distant 
converging striz cut up, as it were, the whole surface into narrow 
bands, the terminations of these bands being serrated projections in 
P. problematicus, but in this species they come to an even edge on 
the notched border. 
Ovisacs (?), Plate XIV [Plate 25] figs. 13, 13*.-— The egg- 
packets (Parka), found in plenty with this species at Trimpley, show 
the membranous veil in several cases. The ova are of considerable 
size, generally oval, and placed a little apart in the younger packets, 
fig. 13, but they become hexagonal or polygonal, from mutual 
pressure, in the older ones, figs. 13*. 
Localities—Base of the OLD RED SANDSTONE, at Lud low Rail- 
way Station (abundant); at Trimpley, north of Bewdley, associated 
with Pteraspis Banksii. (Mr. G. E. Roberts’ Cabinet.) 
