XIII 



PHYLUM CHORDATA 



347 



are separate. In the pectoral arch the scapula is very large, the coracoid small, 

 and the pro-coracoid absent. The pubis in some Dinosauria has a remarkable 



FIG. 957. Iguanodon bemissartensis. One-sixtieth natural size. co. coracoid ; is. 

 ischium ; p. pubis (pectin eal process); pp. post-pubic process (pubis) ; / IV, IV, digits. 

 (From Zittel, after Dollo.) 



slender prolongation (Fig. 957, pp.) running downwards and backwards from the 

 body of the bone parallel with the ischium, an arrangement not found else- 

 where except in Birds ; 

 a pubic symphysis does 

 not always occur. In 

 certain points in the 

 structure of the hind- 

 limb itself some of the 

 Dinosauria also bear a 

 resemblance to Birds. 

 The teeth, which are 



usually compressed and Hl ;: V':i', \^Ml^\iU MF'.eWB^ M 3 



may have serrated 

 edges, are sometimes 

 placed in sockets, some- 

 times in grooves. 



Iguanodon (Fig. 957). 

 one of the best-known 

 genera, attains the 

 length in the case of 

 one species of over 30 

 feet. The limb-bones 

 are hollow. The ischium 



and pubic process are long and slender, and inclined backwards and down- 

 wards parallel to one another. The hind-foot was digitigrade, i.e. the weight 

 was supported on the phalanges of the three digits, and the elongated meta- 



Fio. 958. Teeth of Iguanodon Mantelli. A, from the 

 inner, B, from the outer side. (From Zittel, after Mantell.) 



