the Head in Ornithosaurs. 29 



(downward and forward process of the) frontal behind, the 

 eyes, and completes the orbit. The malar bone by itself, 

 if distinct, might be compared to the mammalian malar. 



In lizards malar, quadrato-jugal, and postfrontal bones 

 exist, but their relations are different from what is seen in 

 Ornithosaurs. The lizard quadrate is commonly vertical, and 

 the quadrato-jugal is attached to its proximal end, while the 

 orbit is completed after the mammalian plan by the (post-) 

 frontal and malar, and the quadrato-jugal does not penetrate 

 the suture between these bones, as it does in Ornithocheirus. 



In Crocodiles there is still the same series of bones, with 

 the malar and quadrato-jugal squamous : but they do not 

 come near to Pterodactyles ; for the quadrate is directed back- 

 ward, while in all Ornithosaurs it is directed forward ; and 

 the quadi-ato-jugal, although attached throughout its length to 

 the quadrate, does not enter into the orbit, but into the tem- 

 poral fossa, and it cannot be said similarly to divide the post- 

 frontal and malar bones. 



In the llhynchocephalia, typified by Sjjhenodon, there is but 

 one bone between the maxillary and the vertical quadrate ; 

 and that bone Dr. Gunther names the malar. But at the back 

 of the orbit the postfrontal and malar bones are separated by 

 a bone named by Dr. Gunther the quadrato-jugal, which 

 meets the squamosal behind, but is entirely separated from 

 the quadrate bone; so that among none of the types which are 

 correctly called reptiles is the resemblance to our Ornitho- 

 saurians very close. 



In birds it is certainly more distant, owing to the rod-like 

 form which these bones take ; but if the bones had assumed a 

 squamous character, and united with the upper boundary of 

 the orbit, the skull in these matters would be essentially avian. 

 Accordingly, with such wide divergences from all other ani- 

 mals, coupled with its own peculiar characters dependent upon 

 the forward direction of the quadrate bone, and the uncertainty 

 about the precise condition of the bones in Ornithocheiridse, I 

 find a difficulty in arriving at any more definite conclusion 

 than that the general relation of these bones is more like what 

 is seen in reptilian types than among birds and mammals. 

 But in no reptile is there a similar condition, and perhaps the 

 nearest reptile type is Sphenodon. 



No Oridthosaurian hitherto figured displays the true struc- 

 ture of the palate. The most instructive specimens are those 

 figured in the well-known memoirs of Goldfuss and Quenstedt. 

 And as Prof. Queustedt's description of the skull in his Ptero- 

 dactylus suevicus makes known some points which do not ap- 

 pear in Von Meyer's general account, I translate what is said 



