Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/97

 AND AYES OF NORTH AMERICA. 91 number of the metatarsals. Thus so far as known, according to Owen, Hylaeosaurus Mint. had three closely approximate metatarsals. In Hadrosaurus they are elongate, but their number is unknom n. In Iguanodon, Owen represents a fourth, but rudimental metatarsal, the hind foot being still three-toed, while in the more ancient genus Scelido-saurus, the same authority gives four shortened metatarsals, of which the smallest supports a digit ; and a fifth rudimental metatarsus, which supports no digit. In Stenopelix there appear to be five digit bearing metatarsals according to Von Meyer. This order is then probably divisible into the following families : I. Teeth in several rows forming a vertical pavement ; metatarsals 1 three. HADROSAURIDAE. Embracing the genus Hadrosaurus, Leidy. II. Teeth in a single row, cutting ; three digit bearing metatarsals. IGUANODONTIDAE. Genera Igimnoclon Buckl. Hylaeosaurus Mant. 2 Palaeoscincus, Leidy. Teeth in a single row, cutting ; four digit bearing metatarsals. SCELIDOSAURIDAE. Genera Scelidosaurus, Owen. Stenopelix Myr. (1 teeth). The last named genus is known from a single skeleton, in which according to Von Meyer, the sacral vertebrc✓ are all distinct. It is perhaps an immature individual. Proc. Ac. Nat. Sci. Phila., 1858, 218. pestles, Leidy 1. c. • IIADROSAUR US, Leidy. Cretaceous Reptiles N. Aro., 76. Trachodon, Leidy, L. C. 1856. ? T1 es- This genus embraces at least two species which are among the most gigantic terrestrial animals of which we have any knowledge. They represent the Iguanodon of the old continent, whose species is similar in bulk. The two genera, however, differ in man) details. The teeth, as above noted, are different. The spines of the dorsal vertebral. instead of being fiat anteriorly, are smaller and slender subcylinclric. Most of the characters of this genus have been given by Leidy in his description of H. foulkii. I add a more complete examination into the characters of the scapular and pelvic arches, which are but lightly treated.of in the " Cretaceous Reptiles of N. America." Scapula.-Here may be introduced a description of certain massive bones of two indi-viduals of a species of Dinosaur. I had formerly admitted the possibility of their pertinence to the pelvis of Hadrosaurus, but the discovery of that element in the II. foulkei, indicates that another place must be sought for them.