208 REPTILIA. 



extension of the depressed ilium is very marked. The pubis is spatulate 

 in form and its post-pubic process is extremely slender, not so long as the 

 much produced ischium. The femur is characterized by a prominent 

 pendent trochanter on the postero-inner face of the shaft. The tibia and 

 fibula are approximately as long as the femur. The astragalus and calca- 

 neum, as usual, form the proximal row of the tarsus, and two elements 

 have been observed in the distal row. Digit no. i is represented only by 

 a rudiment of its metatarsal, and no. v is wanting, so that the hind foot 

 is tridactyl. It is digitigrade with broad, claw-shaped, ungual phalanges, 

 and the phalangeal formula is 0, 3, 4, 5, 0. The fore limbs are not much 

 more than half as long as the hind limbs, and the animal is proved by foot- 

 prints to have walked in a kangaroo-like attitude. The back is strength- 

 ened by ossified tendons extending across the neural spines. No dermal 

 armour has been observed. The typical species is Iguanodon mantelli 

 from the Lower Greensand of Maidstone, Kent, and the Wealden of Ber- 

 nissart, Belgium, measuring 5 or 6 metres in length. A larger species, 

 8 to 10 metres in length, from the Wealden of Bernissart and S. E. 

 England, is named 7. bernissartensis or 1. seelyi. Fragmentary remains 

 also occur in the Purbeck Beds, and an imperfect skeleton of a nearly 

 similar Dinosaur, of small size, has been found in the Kimmeridge Clay 

 of Oxford. 



Claosaurus (fig. 128). One of the latest genera of Dinosaurs, in many 

 respects much specialized. The skull is much like that of Iguanodon 

 with edentulous premaxillse, but with enormous narial openings, and 

 destitute of supraorbital bones. There are 30 presacral vertebrae, 9 sacrals 

 fused together, and about 60 caudals. All the presacral vertebrae are 

 opisthocoalous, and even the hindermost bear free ribs. The anterior 

 caudal vertebrae are also opisthocoelous, and the first and second do not 

 bear chevron bones ; behind these the chevrons are very long. The back 

 is strengthened by ossified tendons extending across the neural spines. 

 The limb-bones are solid, and the fore limbs are unusually small compared 

 with the hind limbs. The scapula is large and much curved, the coracoid 

 very small and perforated by a large foramen. Bones resembling the 

 ' supposed paired sternals of Iguanodon have also been found. The humerus 

 is comparatively short, with a prominent radial crest ; the stout ulna is 

 slightly longer than this and exhibits a conspicuous olecranon process. 

 The carpal bones are imperfecbly ossified, and the manus is elongated ; 

 there are only three functional digits (n iv) with elongated metacarpals 

 and three phalanges in each, but digit I appears as a rudiment with two 

 phalanges. The functional digits are hoofed. In the pelvis, the upper 

 border of the ilium is considerably overturned, the pubis is remarkably 

 large and expanded, with a much-reduced post-pubis, and the shaft of the 

 ischium is greatly elongated. The femur is long and straight, with the 

 large trochanter at its middle. The tibia and fibula are shorter than the 

 femur, while the astragalus and calcaneum remain free though closely 



