28 Mr. H. G. Seeloy on the Structure of 



bones reduced to a rod which unitr-d tlic distal end of the 

 quadrate hone with the ]);ilatal margin of the maxilLary bone, 

 then thei*e would be nothing to distinguish that part of the 

 Ornithocheiroid skull from the bird's skull. And hitherto no 

 evidence has been found of the existence of either this bone or 

 the malar in Cretaceous genera. 



In another point of some importance there is a lack of evi- 

 dence : no trace has been found of the existence in Cambridge 

 fossils of the middle hole of the skull between the orbit and 

 narine ; and as the perforation docs not exist in the Ornitho- 

 saurs Ptarodactyhis longicollum and P. Kochi, I have not 

 outlined it in the diagram. 



So that, to state the case of these Omithosaurs separately, 

 on the evidence at present known, it is found that the only 

 points in which the skull differs from that of birds, are in the 

 vertically expanded quadrato-jugal bone and the apparent 

 expansion of the ethmoid to close in the front of the brain. 

 Yet these characters, though minor in kind, are a wide diver- 

 gence from birds, the latter one being seemingly unparalleled 

 among Vertebrata, and the former implying an expanded 

 squamose malar bone, and probably a developed postfrontal. 

 Therefore there is reason to anticipate that in these bones 

 Cambridge Pterodactyles Avill be found to approximate towards 

 otlier Ornithosaurs, and, like them, to diverge from birds. It 

 may then be appropriate to examine into their bearing on the 

 animal's affinities. 



In the first place, so far as can be judged from published 

 figures, there is no absolutely conclusive evidence in any 

 Pterodactyle Avhether the malar bone has a distinct existence ; 

 it might even be united to the maxillary, or, with less im- 

 probability, to the quadrato-jugal. Perhaps the strongest 

 evidence for its separate existence is offered by the Cam- 

 bridge specimens, where the quadrato-jugal appears to form 

 part of the basal margin of the orbit, and clearly receives 

 a bone in front which must also have entered into the orbit, 

 while apparently nearly the whole of the maxillary is oc- 

 cupied in forming the back of the nostril, and there is no 

 reason for suspecting that it extended back to the orbit ; 

 so that the existence of a separate malar bone is highly pro- 

 bable. And although no one can be more convinced of the 

 fallacy of reasonings founded on imperfect knowledge of facts 

 (the arsenal of erroneous ideas), I think that the existence of 

 this malar bone may, on the evidence, be assumed. 



It is evident, then, that by the existence of a quadrate and 

 quadrato-jugal, these animals differ from mammals, where 

 sometimes, as among ruminants, the malar unites with the 



