Vol. 69. J SKELETON OF OBNITRODESMUS LATIDEXS. 415 



The pre-pubic bones of Scajdior/naiJius and OmiiJwdesmus were 

 probably spatulate, as in DimorpJiodon. If so, they differed from 

 the fan-shaped form characteristic of Pterodactylus, and from the 

 curved band-like form seen in liliamphorlujnchus, Oniithostoma, and 

 Nyctosaurus. 



The terminal head and neck of the femur and the straight shaft 

 in Ornithodesmus separate it from all other genera, where the head 

 and neck are more or less inclined away from the shaft, which was 

 more or less curved. In late forma the great trochanter became 

 very robust. 



The bones of the foot in most of the type-specimens are either 

 imperfectly preserved, or not discovered. 



The widely-divergent characters of Ornithodesmus from all 

 known types make it necessary to form a new family, the 

 Ornithodesmidre. I offer, as best denoting our present know- 

 ledge, the following classification : — 



I. Sub-Order: Scaphognathoidea. 



Skull an open framework of bone, all fossa; very large. Nasal arid 

 preorbital vacuities separated. Concave liza*d-like occiput. 



Family: Scapkognathidae. 



Skull short, not produced into a rostrum. Jugal V-shaped, and united 

 with the supratemporal arcade. Dorsal vertebra not fused into a notarium. 

 Sacral ribs not ancbylosed. Long or short tail. Deltoid crest of humerus 

 wing-like, with the superior border concave. Wing-metacarpal shorter 

 than half of the forearm. ? Pre-pubic bones spatulate. 



'Sub-Family : S c a p h g n a t h i n a;. 

 Short tails. 



Genus : Scaphognathus. 



Sub- Family : Dimorphodon tin as. 

 Long tails. 



Genus : Dimorphodon. 



Family: Ornithodesmidoa. 



Skull elongated. Six lateral fossa; present. Orbits incomplete. Jugal 

 separated from the upper, and the jugal and quadratojugal from the lower, 

 temporal arcades. Maxilla united witb the quadrate, without the inter- 

 vention of the j ugal or the quadratojugal. The last tooth of the upper jaw 

 overlaps the loner jaw, and the last two of the lower fit into slots in the 

 upper. Notarium present, consisting of six vertebra;. No supra-neural 

 plate. The first and last pair of transverse processes are equal in length, 

 the median pair shorter, all distally unanchylosed. Sternum with a 

 large median keel, no anterior spine-like projection, a small lateral ex- 

 pansion of the sternal plate, coracoid articular facets overlapping each 

 other and prolonged on to the lateral surfaces of the keel. Deltoid crest 

 of humerus spiral. Eadius decussating the ulna distally. Wing-meta- 

 carpal equal in length to half of the forearm. 



Genus Ornithodesmus. 

 Nares posterior to all teeth. Orbits far behind the quadrato-mandibular 

 •articulation. Teeth lancet-shaped, compressed laterally, vertically placed, 



