60' ME. K. LYDEKKER OlS A jOJW 



the Wealden form from M. BucMandi, and still more from the 

 Kimeridgian M. insignis of Deslongchamps, and I am accordingly- 

 disposed to adopt Dr. Koken's name for the former. 



Conclusion. — In conclusion I may observe that the foregoing 

 brief survey of the English generic forms referable to the Sauropoda 

 shows how extremely unsatisfactory is our knowledge of these 

 reptiles, and how little hope there is of arriving at any certain con- 

 clusion as to the number of genera that should really be maintained. 

 This unsatisfactory state of things teaches us, I venture to think, a 

 lesson as to the extreme caution which should be observed in 

 founding new genera in this and other groups, upon the evidence of 

 one or two bones, or even fragments of a single bone, and still more 

 upon yet more unsatisfactory specimens. It is the easiest thing in 

 the world to apply a new name to any specimen that turns up ; but 

 when we find one genus founded upon a humerus, another on a 

 cervical vertebra, a third on a caudal vertebra, and a fourth on 

 a cast of a sacrum, the evil results of such a system are self-appa- 

 rent. In the old days of Palaeontology it was natural and right 

 that every specimen of importance should be definitely named ; 

 but I venture to suggest that in the present state of our know- 

 ledge the time is past for apphing new generic terms, except in 

 those cases where it can be shown with almost complete certainty 

 that the forms to which such terms are applied are distinct from 

 all that have been previously named. It would, indeed, be advan- 

 tageous if we were beginning de novo to take one particular part of 

 the skeleton, and say that on the evidence of that part, and that part 

 alone, generic terms should be made ; but now, even if we could 

 get such a rule assented to and enforced, its application would not 

 be of much value, owing to the heterogeneous materials on which 

 our genera have been founded. Still, even now, something may be 

 done in this direction, if Palaeontologists will but refrain from 

 applying new generic names to specimens belonging to parts of the 

 skeleton totally different from those upon which allied genera have 

 been founded. A specimen, to my mind, is quite as interesting and 

 quite as important if left without a generic name, as it is when 

 made the type of a so-called new genus to which we are unable to 

 assign its proper position in the system, and which, for all we 

 know, may be not separable from a form which has already received 

 one or more names. 



EXPLANATION OF PLATE III. 



Figs. 1 & 2. Palatal (1) and outer (2) aspect of the greater portion of a right 

 maxilla, probably referable to Ornithopsis Hulkei, from the Wealden 

 of the Isle of Wight (Brit. Mus. No. E. 751). -J nat. size. 



3. Anterior extremity of the same specimen. Nat. size, 



4. Inner aspect of a tooth referable to the same species as the preceding, 



from the Wealden of Brixton, Isle of Wight (Brit. Mns. No. E. 964). 

 Nat. size. 



In figs. 1, 3, a indicates the tooth; while in fig. 1, h shows the 

 shell of a tooth. 



