22 
THE GEOLOaiST. 
but is only connected with the requirements of the bones of the animal, 
and may be long or round in the same animal as occasion requires." 
After writing the above remarks, Mr. Dennis received from Mr. 
Henry Catt a portion of bone from the chalk of Brighton, which 
exhibited precisely these characters. AVriting of it, he says : — 
" The Haversian tubes are principally longitudinal ; the lacunae are long, 
like those on the bill of the pelican, — and, indeed, the Haversian tubes 
may nearlj^ compare, especially in size. There is, however, a peculiarity 
I was not]3repared for, having observed it in no bird-bones, though I have 
noticed something like it in the frog. It is the way in which the 
lacunae cross.* There appears to be a set running longitudinally, and a 
set above them running in the opposite direction, which gives a very 
marked and peculiar cliaracter to the bone, and makes me think the bone 
from the Chalk, and which is a hollow bone with very thin walls of a pe- 
culiar texture,t is Pterodactyle bone. Another thing confirms me in this 
view : the canaliculi are not numerous, like those of birds (fig. 7 and 14) ; 
if so, this is a further confirmation of those general principles I laid down 
in a previous paper on the characteristics of bone, — the Pterodactyle, 
though it could fly like the bird or bat, yet showing its saurian characters, 
both outwardly and inwardly in its bones." 
Mr. Dennis then takes up that topic with which we are now most 
interested, —a bone from the Stonesfield slate, which he assigns to the 
class of birds. The fossil bone which Mr. l)ennis submitted to exa- 
mination was selected from several other supposed fossil bones of 
birds from that stratum, belonging to Mr. Adams, of Buriton, Peters- 
field. It was selected as one of the greatest interest, from its strik- 
ing similarity in structure to the humerus of the heron. It belonged, 
according to Mr. Dennis, to a smaller kind than our common heron, 
and appears from a drawing which, with some fragments only of the 
bone, was all that he received, to be the distal end of the humerus of 
the heron. The bone possesses " quite the texture of bird-bone in 
its outward appearance, and is decidedly different from that of the 
Pterodactyle from the Chalk, wliich looks rather silky, an appearance 
apparently caused by fine lines on its surface, which the bird-bone is 
free from. The vertical section of a portion of tbis bone gives the 
following characters : — 
" Haversian tubes for a bird of moderate thickness ; reticulate, but 
without any precise form or size in the loops, but rather a marked irregu- 
larity is shown, some appearing square, others triangular, others oval, — 
in fact, of all shapes and sizes ; sometimes they somewhat interlace ; they 
do not entirely maintain a uniform diameter, the reiiculations are inclined 
to form combinations, which produces a variety in their appearance, some- 
times two or three of a similar shape and size uniting. The lacunae are 
numerous, small ovals and round, but more pointed ones than round. 
The canaliculi are fine, much branched, and veiy numerous." 
That tliis is the bone of a bird, from the evidence adduced, Mr. 
* lu a footnote, IMr. Dennis says he has observed something like this crossing in the 
skulls of some birds and iu the hone-platcs of the Armadillo. 
t Such arc ihe familiar characteristics of the known Pterodaclylc bones from the 
Chalk aiid Jurassic strata. — Ed. Geol. 
