1891.] Remarks on Reptiles Called Dinosauria. 451 
tiles, without any close relation between each other. The Dino- 
sauria do not exist. ; 
2. The so-called Dinosauria contain three groups of rep- 
tiles, which ought to be called Iguanodontia, Megalosauria, and 
Cetiosauria. | 
The distinctive character of these three groups are: 
IGUANODONTIA. 
Brain-case compleétely ossified; a well-developed alisphenoid ; 
no epipterygoid (columella) ; premaxillaries with a posterior outer 
process extending between nasals and maxillaries, excluding 
maxillaries from nasal openings; jugals fixed to a special process 
of the maxillary outside the alveolar border; posterior alveolar 
end of maxillaries free; not connected with jugals or quadrato- 
jugals ; quadrate directed forward; mandible with a distinct pre- 
dentary bone; dentary with greatly developed coronoid process ; 
sacral vertebrze with ribs and diapophyses united, intervertebral ; 
pubis consisting of two branches ; the anterior one ectopubis (pec- 
tineal process, prepubis) greatly developed: the entopubis 
directed backwards, well developed or rudimentary ; ilium very 
much extended in front and also behind. 
CETIOSAURIA. 
Brain-case completely ossified; a well-developed alisphenoid ; 
no epipterygoid (columella) ; premaxillaries not excluding maxil- - 
laries from nasal opening; jugal and quadratojugal forming a 
continuation of the posterior border of the maxillary in the same 
plane; quadratojugal in connection with maxillary; quadrate 
directed forwards; mandible without predentary bone; dentary 
without coronoid process ; sacral vertebra with ribs only ver- 
tebral; pubis consisting of one branch, the entopubis only, 
directed forwards. 
MEGALOSAURIA. 
Brain-case ‘not ossified in front; no ossified alisphenoid; an 
epterygoid (columella); premaxillaries not excluding maxillaries 
from nasal opening; jugal connected with alveolar end of maxil- 
_ lary, on the same plane; quadratojugal free from maxillary ; quad- 
