130 Mr. H. G. Seeley on Prof. Owen's 
gives of the skull in Ornithosaurians from the Lithographic 
slate*. 
« The skull of the Pterodactyles, which Oken placed between 
Chameleon and Crocodile, after all can only be compared to 
the skulls of birds and of lizards. The preponderating resem- 
blance to the bird's head cannot be disputed ; but, on the other 
and, it has opposed to it a surprising dissimilarity in certain 
parts, which incline to the type of the Sauria. Several spe- 
cies are characterized by an exceedingly depressed snout, 
which occurs more frequently in birds. In other respects, 
also, the general shape of the head is more like birds than 
it is like reptiles, which show a cranium more or less flattened. 
The bats, which deserve notice as flying Vertebrata, are en- 
tirely mammalian animals, and totally different, especially in 
their heads. In Pterodactyles, as in birds, the bones of the 
skull blend together so imperceptibly that their sutures at 
best are only indistinctly seen, and are sometimes obliterated ; 
while even in full-grown reptiles they are all to be made out 
with great distinctness. There is the more difficulty in ascer- 
taining the structure of the Pterodactyle skull, since generally 
only the lateral aspect is exposed, and hence we get scarcely 
any information about its upper and under surfaces. Among 
the skulls which are die. from the side, information is at 
times afforded by those in which the parts have suffered some 
displacement; but the separations so produced are to be ac- 
cepted with great caution, for they do not always coincide 
with the real boundaries of the bones. 
* From ‘Zur Fauna der Vorwelt. Reptilien aus dem lithographischen 
Schiefer, &c.,’ von Hermann yon Meyer, (Frankfurt am Main, 1859. 
Folio) pp. 15,16, 
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