22 



THE GEOLOGIST. 



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. "Writing 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 nearly compare, especially in size. There is, however, a peculiarity 

 I was not prepared 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 

 lacunse 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 character 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,f 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 clown 

 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 boDe which Mr. Dennis 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, which 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 this 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 reticulations 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 lacuna? are 

 numerous, small ovals and round, but more pointed ones than round. 

 The canaliculi are fine, much branched, and very numerous," 



That this is the bone of a bird, from the evidence adduced, Mr. 



* In a footnote, Mr. Dennis says he lias observed something like this crossing in the 

 slculls of some birds and in the bone-plates of the Armadillo. 



f Such an 1 (he familiar characteristics of the known Pterodactyle bones from the 

 Chalk and Jurassic strata. — Ed. Geol. 



