TRANSACTIONS OF SECTION D. 765 



with anterior margins united. Astragalus without ascending process. Five digits 

 in manus and in pes. 



Genera: Zanclodon, ? Teratosaurus. 



4. Family Anchisaurida. Vertebrae hi-concave. Pubes rod-like. Five digits 

 in manus, and three in pes. 



Genera : Anc/iisaurus (Megadaetylws), ? Bathygnathus, ? Clepsysaurus, Palceo- 

 saurus, Thecodontosaurus. 



Sub-Order Cgelttria. 



5. Family Cccluridce. Vertebrae and bones of skeleton pneumatic. Anterior 

 cervicals convexo-concave ; remaining vertebrae bi-concave. Cervical ribs co- 

 o'ssified with vertebrae. Metatarsals very long and slender. 



Genus: Cwlurus. 



Sub-Order Cohpsogxatha. 



6. Family Compsognathidee. Cervical vertebrae convexo-concave ; remaining 

 'vertebrae bi-concave. Three functional digits in manus and in pes. Ischia with 

 long symphysis on median line. 



Genus : Compsognathus. 



Sub-Order Ceratosatjeia. 



7. Family Ceratosauridce. Horn on skull. Cervical vertebrae plano-concave ; 

 remaining vertebrae bi-concave. Pubes slender. Pelvic bones coossified. Osseous 

 dermal plates. Astragalus with ascending process. Metatarsals coossified. 



Genus : Ceratosaurus. 



The four orders defined above, which the author first established for the recep- 

 tion of the American Jurassic Dinosaurs, appear to be all natural groups, well 

 marked in general from each other. The European Dinosaurs from deposits of 

 corresponding age fall readily into the same divisions, and, in some cases, 

 admirably supplement the series indicated by the American forms. The more 

 important remains from other formations in this country and in Europe, so far as 

 their characters have been made out, may likewise be referred with certainty to 

 the same orders. 



The three orders of Herbivorous Dinosaurs, although widely different in their 

 typical forms, show indications of approximation in some of their aberrant genera. 

 The Sauropoda, for example, with Atlantosaurus and Brontosaurw, of gigantic size, 

 for their most characteristic members, have in Morosaurus a branch leading 

 towards the Stegosauria. The latter order, likewise, altffough its type genus 

 represents in many respects the most strongly marked division of the Dinosaurs, 

 has in Scelidosaurus a form with some features pointing strongly towards the 

 Ornithopoda. 



The Carnivorous Dinosauria now best known may all be placed at present in a 

 single order, and this is widely separated from those that include the herbivorous 

 forms. The three sub-orders here defined include very aberrant forms, which 

 show many points of resemblance to Mesozoic birds. Among the more fragment- 

 ary remains belonging to this order, this resemblance appears to be carried much 

 further. 



The Amphisauridce and the Zanclodontida, the most generalised families of the 

 Dinosauria, are known only from the Trias. The typical genera, however, of all 

 the orders and sub-orders are Jurassic forms, and on these especially the present 

 classification is based. The Hadrosauridoz are the only family confined to the 

 Cretaceous. Above this formation there appears to be at present no satisfactory 

 evidence of any Dinosauria. 



The peculiar orders Hallopoda and Aetosauria include carnivorous reptiles 

 which are allied to the Dinosauria, but they differ from that group in some of its 

 most characteristic features. In the former genus, the entire limbs are crocodilian, 

 and this is also true of the dermal covering. In both of these genera there are but 

 two sacral vertebrae, but this may be the case in true Dinosaurs, especially from 



