8 PROCEEDINGS OF THE GEOLOGICAL society. [June 9, 
say, those represented by figures la, 16 and 3 of Plate 13, illustrating 
Dr. Mantell’s paper, and now numbered 453 in the British Museum. 
Of the bone represented by figure 6 in Dr. Mantell’s paper, there is 
nothing said in this communication further than a general reference 
to the nature of the bones treated of in the concluding sentence of 
the paper, which is thus expressed :—“ We have no satisfactory evi- 
dence, however, of the existence of birds in the Wealden.’ 
On the 7th of January 1846 Dr. Mantell read a paper to the Geo- 
logical Society, entitled “On the Fossil Remains of Birds in the 
Wealden Strata of the South of England,” in which he questions the 
propriety of the conclusions arrived at by Professor Owen; but as 
neither of the authors of these papers appeared to have examined 
microscopically the structure of the bones in question, I resolved to 
endeavour to remedy this omission. 
Upon submitting some minute fragments from the fractured end 
of the shaft of the bone represented by figures la and 16 of Dr. 
Mantell’s paper, and figures 1 and 2 of Professor Owen’s communi- 
cation, published in No. 6 of the Quarterly Journal of the Geologi- 
cal Society, 1 found the bone-cells, as represented at fig. 8. Pl. I., 
to coincide in every respect with those of the Pterodactyl remams 
before described in this communication. An average of five of them ~ 
gave the following dimensions :—length ~1, inch; greatest diame- 
ter = inch; and the number, proportion and mode of disposition 
of the cells, and of the canaliculi radiating from them, were precisely 
in accordance with those of the recent as well as of the fossil reptilia. 
We may therefore justly infer that the latter conclusion of Professor 
Owen regarding this bone is the correct one, and that the specimen 
is truly Pterodactylian. But not so with regard to the larger bone 
represented by figure 6 in Dr. Mantell’s paper in the Transactions of 
the Geological Society of June 10, 1835. Fragments from about the 
middle of the shaft of this bone exhibited the characteristic cells m 
a very distinct and satisfactory manner, but, unlike the former, they 
agreed in every respect with those of birds as represented at fig. 9. 
Pl. I. An average of five afforded the followmg measurements :— 
length 5}, inch; greatest diameter ;3;5 inch. The proportional 
characters of the bone-cells, and the bird-like build of the bone itself, 
leaves therefore little reasonable doubt of its beg truly the remains 
of a member of the class Aves. 
I have examined many other specimens of bones from the Wealden 
and the Stonesfield slate, as well as from the Chalk, and in every in- 
stance the class to which they belonged might, I am of opinion, be 
readily and correctly determined ; but as the specimens I allude to 
have not been made especial subjects of doubt or discussion, I shall 
abstain from increasing the length of this communication by deseribmg 
them. There is one case only to which I shall allude on the present 
occasion, and that is a specimen described and partly figured in page 
22 of the first part of the London Geological Journal as “‘a reptile 
or fish” from the chalk of Kent. The possessor of this valuable 
fossil, Mr. Toulmin Smith, has kindly furnished me with a small 
fragment of the jaw, which exhibits very distinctly one of the pecu- 
