ORDER DINOSAURIA. 1 1 59 



with the typical species of the genus in having the pollex modified 

 into a conical spine, and thereby differed from Camptosaurus, 

 although indicating how the one genus passed into the other. It 

 is not improbable that the large Iguanodont from the Upper 

 Jurassic of the United States, described as Camptosaurus amfilus, 

 should be referred to this group of Iguanodon, since it has but 

 three functional digits in the pes. 



With the genus Camptosaurus (Camptonotus), we come to forms 

 which are usually of smaller size than the preceding. It occurs 

 typically in the Upper Jurassic of North America ; but certain 

 forms, from the English Oxford and Kimeridge Clays, to the latter 

 of which the name Cumnoria has been applied, as well as a Wealden 

 species, do not appear to be generically separable. This genus has 

 teeth of somewhat simpler structure than those of Iguanodon, and is 

 further characterised by the flattened haemal surfaces of the centra 

 of the sacral vertebrae, which appear to have remained separate 

 throughout life ; by the short preacetabular process of the ilium 

 (fig. 1052) of the type species ; by the equality in the length of the 

 pubis and ischium ; by the pendant, or downwardly directed, inner 

 trochanter of the curved femur (fig. 1057, b) ; and the presence of 

 five digits of normal structure in the manus, and typically of four 

 in the pes. The length of the femur of the type species is some 

 2 1 inches. The English forms are not fully known ; but so far as 

 this is the case they agree in essential characters with the type : the 

 structure of the manus and pes is, however, unfortunately unknown. 

 C. leedsi, of the Oxford Clay, is known only by the femur (fig. 

 1057, b), which measures a little over one foot in length; while in 

 the Kimeridgian C. Prestwichi (the type of Cumnoria) we are ac- 

 quainted with the greater part of the vertebral column, in which the 

 dorsals have tall neural arches, while the ilium has a long preace- 

 tabular process like that of Iguanodon. The Wealden C. valdensis 

 is typified by a femur. Laosaurus is an allied form from the Upper 

 Jurassic of the United States, distinguished by its amphiccelous 

 cervical vertebrae. The imperfectly known Cryptodraco (Crypto- 

 saurus), from the Oxford Clay of England, is characterised by the 

 great stoutness of the femur, which exceeds a foot in length, and 

 has a straight shaft, with an inner trochanter like that of Iguanodon 

 bernissartensis, but differs from the corresponding bone of all other 

 members of the family in the absence of a groove on the anterior 

 aspect of the lower end between the condyles. 



Lastly, we come to the consideration of Hypsilop/zodon, the 

 smallest and least specialised representative of the family, which 

 is now well known to us through the labours of Mr J. W. Hulke. 

 In this genus, which occurs in the Upper Wealden of England, the 

 general structure of the pelvis, as well as the pendant inner tro- 



vol. 11. s 



