424 DINOSAURIA 



pointed ribs. Tail long with well-developed chevrons. The 

 skull is long and pointed, composed of thin bones, which have 

 lost most of the sutures ; with large lateral, temporal, and 

 pre-orbital, but without supratemporal, foramina. Premaxillae, 

 maxillae, and mandible with numerous slender and rather long, 

 conical, alveolar teeth. 



Order III. ORTHOPODA, 



Each puMc hone consists of an anterior or pre-puhic and a 

 posterior or post-puhic branch, neither of which forms a 

 symphysis. Premaxillae without teeth. With a premandi- 

 bular predentary piece. Herbivorous. 



The so-called pre-pubis is homologous with the pubis of most 

 recent reptiles, and with the pectineal process of birds, while the 

 " post-pubis " is homologous with the processus lateralis of 

 Chelonians and Saurians, and with the " pubis " of birds. The 

 right and left halves of the pubis remain widely asunder ventrally. 

 In many cases the post-pubis, always directed obliquely backwards, 

 lies closely against the shaft of the ischium, which always forms 

 a distal syndesmosis, or a symphysis, with its fellow. The fore- 

 limbs are usually very short, provided with five or four short 

 and strong fingers. The hind-limbs are long and strong, mostly 

 with three, sometimes with four functional short toes, either 

 plantigrade (Stegosauki) or digitigrade (Ornithopoda). Femur 

 with an inner distal, or fourth, trochanter. The dentition is of 

 the herbivorous type, restricted to the dentaries of the mandible 

 and to the maxillary bones, leaving the whole or the greater part of 

 the premaxillaries free. The additional " predentary " piece of the 

 mandible is possibly a calcified, but originally horny, pad. The 

 teeth are greatly compressed laterally, and finely serrated, but are 

 much ground down by use ; several rows of successional teeth lie 

 on the inner or lingual side. The skull is strongly built, with 

 large anterior nasal openings ; pre-orbital foramina very small or 

 absent ; orbits completely encircled by bones ; supratemporal 

 foramina small, lateral foramina large. Quadrate large, vertical 

 or slanting slightly forwards. The vertebrae are solid, not 

 hollow ; sacrum consisting of four, five, or more vertebrae ; ribs 

 bifurcated, the capitula carried either by the centra, or moved up 

 to the diapophyses of the neural arches ; chevron-bones numer- 



