Prof. H. G. Seeley — On the Genus Oniithocheirus. 15 



below these tooth sockets has the surface less well preserved than 

 the upper part, but it was marked by a median inflation below the 

 teeth, and concavities on each side, which converge to a median 

 concavity that becomes continued on the under side of the jaw. 

 The median oblong boss between the teeth appears to have been 

 roughened with two longitudinal grooves, and the whole of this 

 inferior region gives indications of rugosities, as though fleshy lips 

 might have extended forward below the teeth, and there are no in- 

 dications of blood-vessels perforating the bone, such as might have 

 been anticipated if it had been sheathed in horn. The basal oblique 

 truncation which forms a prolongation of this anterior region down- 

 ward and backward is concave in length, a feature seen in no other 

 Greensand Ornithosaur. It is about three and a half centimetres 

 long, and has a shallow median groove about seven millimetres 

 wide, which appears to become shallower as it extends backward. 

 It is margined by convex ridges, which at first round obliquel}' into 

 the sides of the jaw, but make a smaller angle with it as the jaw 

 becomes more compressed from side to side in its backward exten- 

 sion. The fragment which is preserved of the lateral surfaces of the 

 jaw shows smooth bony tissue, is concave from above downward, and 

 nearly flat from before backward, and, as already remarked, rounds 

 into the adjacent bony surfaces. These lateral areas are sub-rhomboid, 

 are preserved for an antero-posterior extent of hardly more than 

 three centimetres, while the depth of jaw indicated by the fragment 

 is six and a half centimetres, probably a good deal short of its depth 

 when perfect. The extreme posterior width of the specimen behind 

 the first pair of palatal teeth is four and a half centimetres, and the 

 width of the jaw where fractured at the postei'ior termination of the 

 base is one and a half centimetre. 



In 1869, in my index to the Eeptilia, etc., in the Woodwardian 

 Museum, I gave a list for the use of students of species which might 

 be founded upon the Pterodactyle remains therein enumerated from 

 the Upper Greensand, and I further grouped these species into two 

 genera, which were named though not fully characterized. Fteno- 

 dactylus was used for twenty-one species, all more or less allied in 

 character to the Pterodactylus SedgwicM of Owen. The other 

 genus, Ornithoclieirus, included three sj^ecies, and had for its type the 

 Pterodactylus simus of Owen, it being mentioned in a note that the 

 genus was distinguished by having no teeth anterior to the palate, a 

 character which inferentially distinguished it from the other new 

 genus. A month or two later, in the beginning of 1870, " The 

 Ornithosauria " was published, and in that book I temporarily 

 abandoned the division of the species into separate genera, not 

 because they seemed to be incapable of definition, but because the 

 species appeared to be capable of division into more than two genera, 

 and I thought it inexpedient to characterize them until the whole of 

 the evidence could be fully put forward, and supported by means of 

 figures. The name Ptenodactyhs was therefore abandoned and the 

 whole of the species described were temporarily referred to Ornitho- 

 cheirus. This genus was defined (p. 112) as having teeth prolonged 



