OKNITHOPODA. 175 



Thecodontosaurus antiquus, Morris 1 . 



The type species. Of small size ; 21 lower teeth. 

 Hab. Europe (England). 



R. 1108. Cast of the greater part of the left ramus of the man- 

 dible. The original is from the Upper Triassic Conglome- 

 rate of Durdham Down, near Bristol, Gloucestershire, and 

 is preserved in the Museum at Bristol ; it is figured by 

 Huxley in the ' Quart. Journ. Geol. Soc' vol. xxvi. pi. iii. 

 figs. 1, 2. Made in tlie Museum, 1887. 



Suborder ORNITHOPODA. 



Premaxilla (when known) edentulous entirely or anteriorly ; no 

 preorbital vacuity ; nares terminal or subterminal ; quadrate elon- 

 gated and slightly inclined forward ; teeth usually serrated, complex, 

 and not set in distinct sockets. Erequently a predentary bone. 

 Vertebrae without internal cavities 2 or zygosphenal articulations; 

 cervicals shorter than dorsals, with free ribs, and either opistho- or 

 amphiccelous ; anterior and middle caudals with postzygapophyses ; 

 chevrons usually closed ; rib-facets of dorsal vertebras either on 

 arches or transverse processes. Pectoral limb much shorter than 

 pelvic ; scapula with proximal extremity greatly or moderately ex- 

 panded, and frequently with the anterior border convex and pos- 

 terior concave ; humerus with head usually well differentiated from 

 tuberosities ; five digits in manus. Ilium shallow, generally with 

 elongated preacetabular process ; pubis directed backwards parallel 

 to ischium, without symphysis, and with large preacetabular (pec- 

 tineal) process ; ischium with obturator process, short or elongated. 

 Femur with straight shaft, generally large inner trochanter, and the 

 head globular, differentiated from upper trochanters, and set nearly 

 parallel to condyles ; astragalus applied to tibia ; metatarsals long 

 or short ; terminal digits of pes either laterally or vertically com- 

 pressed ; feet digitigrade or plantigrade. 



This Suborder is taken (after Cope) to include the Stegosauria of 

 Marsh 3 . The more specialized forms were mainly of bipedal habits. 



1 Cat. Brit. Foss. 1st ed. p. 211 (1843). This name is coimnonly quoted as 

 Eiley and Stutchbury, but it does not occur in either of their memoirs. 



2 If Stenopelix (see Koken, Pal. Abhandl. toI. iii. pi. xxx. 1887) belong to this 

 suborder (with which it agrees in the form of the iliuin) it will be an exception 

 in this respect. 



3 Seeley has proposed to substitute the name Ornithischia for this group, and 

 to make it of ordinal rank. See Rep. Brit. Assoc, for 1887, p. 698, and Proc. 

 R. Soc. vol. xliii. p. 170 (1887). 



