a Pachypod from the ('a)nhriiliji' l'j>per ( I rccnsand. i\01 



the accuracy ot" the method of research. It theretbre seems 

 dcsirahU' that fossil j^roups shouhl be comparable in ma^nii- 

 tiule with the <;cnera and species of true (/. e. living) Keptilia. 



Probably the Folkestone fossil and these from Cambridge 

 occur upon the same horizon ; for the Cambridge animals are 

 usually from the uj)per portion of the phosphatic stratum, and 

 are rarely mineralized witii plmsphates, while the Acantho- 

 pfiolis hon-i(/usj according to Air. lOtheridge *, is from the 

 Chalk-marl, about 8 feet above the Upper Greensand ; and 

 almost all the marine species foimd in the bed, exce|)t Ammo- 

 nites and some of the Echinoderms, are also fossils of the 

 Cambridge Greensand. 



The English Dinosauroids of which the foot-bones have 

 hitherto been figured arc refciTcd to Jli/hrosaun/Sj LjuanoJon^ 

 ScelidosauniSj ami llijpsUojihodon. The metatarsus in Ili/hro- 

 saurus is made of three somewhat slender and greatly elon- 

 gated bones f. In Iguanodon there are three principal meta- 

 tarsal bones, which are less elongated and relatively much 

 stouter than in the specimen referred to Ilf/Ia'osaurus, while 

 there is also a rudimentary slender fourth metatarsal J. In 

 Scelidosaurns there are four moderately elongated metatarsals, 

 of which the lirst is conspicuously short ; and tliere is also, 

 according to Professor Owen, a slender styliform i-udiment of 

 a fifth metatarsal, which is adlierent to the proximal end of 

 the fourth § ; while in the skeleton which Professor Huxley 

 refers to Hypsilophodon (Quart. Joiirn. Geol. Soc. Feb. 1870) 

 the animal is remarked upon as possessing certainly four, and 

 ])erhaps also a slender fifth metatarsal bone, Avhich, from 

 Prof. Owen's figure ||, a})pear to be about as long as 2^ cen- 

 trums of dorsal vertebra?, and rather more slender than the 

 metatarsus of Scelidosaurus. When, therefore, the foot of 

 Acanthoplioh's was found to consist of five well-developed 

 bones, of which the fifth a])pears well capable of carrying 

 phalanges, and the first is singularly massive, the animal was 

 invested with platypodial interest, as probably showing a cha- 

 racter new in the order, and offering a new point of affinity. 



x\t the time in wliich Prof. Owen wrote (1857) some doubt 

 hung over the determination of the terminal segments of the fore 

 and hind limbs ; and this doubt is not to be neglected in inter- 

 prethig the present specimens, notwithstanding the researches 

 of Leidy, Cope, and lluxley on the proportions of the Dino- 

 saurian limbs. 



* Geol. Mag. 1867, vol. iv. p. 68. 

 t Wealden Rept. 1857, part 4, pi. xi. 

 § Oolitic Rept. 1862, part 2, p. 17, pi. x. 

 II Wcaklen Dines. 1854, pt. 2, pi. i. 



I Loc. cit. pis. i.-iii. 



