NOTES AXD QUERIES. 
109 
exhausted ; for my good friend, Mr. Baugh, of Bewdley, wlio Las 
followed up my researches in Worcestersliire by constant and unwearied 
attention, assui'es me that no other specimens can be got from the 
stone brought up from the now fiUed-up quarry. Less is known about 
the tuberculated Cephalaspides than of those whose head-shield is 
ornamented by scale-like area, marked out by the out-cropping of minute 
vascular canals, entering the disk from beneath, and exhausting them- 
selves upon its surface. This true reading of the external appearance 
of C. Lyellli is contained in a paper by Prof. Huxley, in the Quart. 
Joum. Geol. Soc, vol. xiv., p. 270. Equally careful and minute is 
the description there given of the layers which unite to form the 
cephalic shield of Pteraspis. Briefly their characters may be thus 
given — the innermost layer is a thin delicate lamina of enamel, some- 
what nacreous, and occasionally tinged with colour; the middle layer 
is composed of vertical plates of like substance, so arranged as to 
enclose polygonal cells, whose summits or external apertui'es are 
closed by an excessively delicate filmy layer, minutely reticulated ; and 
lastly the outer plate consists of a hard layer, strongly ridged, whose 
summits are turned outwards. In one species I have observed the 
external edges of these ridges to be minutely toothed. Most of the 
characters of this triple armour are shown in the annexed sketch of 
Pteraspis. 
Thus I have briefly called attention to the occun'ence of these fishes 
in several places, though their condition is usually fragmentary, in 
the Old Red of England. 
And so, we bid our adieus to these shield-bearing ancients ; but 
only that we may meet them elsewhere, and obtain from them in 
the field their willing tribute to our scientific treasury. Much has 
been wTitten about them, but more remains to be said. And while 
the story yet to be told is in the careful keeping of an accurate 
natui'alist, any collector who can find and contribute a readable frag- 
ment may be proud of being associated, not only a memoir of 
the earliest kno^Ti fish, but also with that which dignifies the study 
of Cephalaspis and Pteraspis — the history of the first appearance of 
vertebrated life. 
NOTES AND QUERIES. 
Tertiary Strata in Kent. — De.\r Sir, — It has been aptly said by one of 
your correspoudents that deep railway-cuttings, though presenting difficulties 
to the engineer, are great helps to the geologist ; and the sections exposed in 
the new London, Chatham, and Dover Railway, are particularly interesting in 
showing the geological features of East Kent, As one who has taken deep 
interest in the geology of the county, and has studied these cuttings, particularly 
that over the chalk near Canterbury, at Beakesbourn, perhaps I may be permitted 
to give a short account of them, through the medium of yoiu: valuable journal. 
