170 PROF. H. G. SKELEY OX SAURODESMUS ROBERTSONI. 



into two orders, but if this was done the original name must be 

 retained for the typical forms. An analogous instance occurs in the 

 separation by some writers of the Lemuroidea from the Primates, 

 the latter being retained for the typical members of the order. Any 

 other course would be unjustifiable. 



The Author thought that if Mr. Lydekker visited Paris and 

 sought the aid of Prof. Gaudry in making comparisons, he might 

 learn the nature of Dimodosaurus and the relation of the Australian 

 fossil now described to that type and its allies. He used the term 

 " Saurischia " rather than " Diuosauria •' in defining the position of 

 this animal, because new ideas in classification needed new names for 

 their adequate expression. It might be that the groups Ornithischia 

 and Saurischia were provisional, for there were indications of a third 

 group which could not be defined as yet. He thought there could 

 be no more justification for the proposal to restrict the name " Diuo- 

 sauria " to one of these groups than there would be to restrict the 

 term " Mammalia " to the Monotremata or Marsupialia. 



With regard to the Linksfield fossil, he had carefully compared it 

 with every available specimen in the British Museum without finding 

 evidence of near affinity with the Chelonia, though without doubt as to 

 its osteological identification. This was the first necessity in making 

 a determination of the bone. As Mr. Lydekker had been unable to 

 determine whether the bone was a humerus or a femur, he did not 

 know how it was possible for him to have arrived at any reference 

 of it to the Chelonia or any other group. But when the form of 

 the distal end was appreciated as fixing its place in the skeleton, it 

 followed that only in Crocodiles and Ornithosaurs could any parallel 

 be found to the characters of the proximal end, so as to bring it 

 into harmony with the distal end of the bone. He fully admitted the 

 difficulty in restoring the head of the bone in a new type of animal. 



