7^ Royal Institution : — 



the vertebral column completely known, while the sternum and the 

 manus have not yet been obtained in any of the genera. In none 

 has any trace of a clavicle been observed. 



With regard to the characters which have been positively deter- 

 mined, it has been ascertained that : — 



1. Prom four to six vertebree enter into the composition of the 

 sacrum, and become connected with the ilia in a manner which is 

 partly ornithic, partly reptilian. 



2. The ilia are prolonged forwards in front of the acetabulum as 

 well as behind it; and the resemblance to the bird's ilium thus pro- 

 duced is greatly increased by the widely arched form of the acetabular 

 margin of the bone, and the extensive perforation of the floor of the 

 acetabulum. 



3. The other two components of the os innominatumhaYe not been 

 observed actually in place ; indeed only one of them is known at all ; 

 but that one is exceedingly remarkable from its strongly ornithic 

 character. It is the bone which has been called " clavicle " in Me- 

 (jalosaurus and Iguanodon by Cuvier and his successors, though the 

 sagacious Buckland had hinted its real nature *. But these bones 

 are not in the least like the clavicles of any animal which possesses 

 a clavicle, while they are extremely similar to the ischia of such a 

 bird as an ostrich ; and in the only instance in which they have been 

 found in tolerably undisturbed relation with other parts of the ske- 

 leton, namely, in the Maidstone Iguanodon, they lie, one upon each 

 side of the body, close to the ilia. I hold it to be certain that these 

 bones belong to the pelvis, and not to the shoulder-girdle, and I 

 think it probable that they are ischia ; but I do not deny that they 

 may be pubes. 



4. The head of the femur is set on at right angles to the shaft of 

 the bone, so that the axis of the thigh-bone must have been parallel 

 with the middle vertical plane of the body, as in birds. 



5. The posterior surface of the external condyle of the femur pre- 

 sents a strong crest, which passes between the head of the fibula and 

 the tibia as in birds. There is only a rudiment of this stnicture in 

 other reptiles. 



6. The tibia has a great anterior or " procnemial " crest, convex 

 on the inner and concave on the outer side. Nothing comparable to 

 this exists in other reptiles ; but a correspondingly developed crest 

 exists in the great majority of birds, especially such as have great 

 walking or swimming powers. 



7. The lower extremity of the fibula is much smaller than the 

 other ; it is, proportionally, a more slender bone than in other rep- 

 tiles. In birds the distal end of the fibula thins away to a point, 

 and it is a stiU more slender bone. 



8. Scelidosaurus has four complete toes, but there is a rudiment of 

 a fifth metatarsal. The third or middle toe is the largest, and the 



* The so-called ^'coracoid" oi Megcdosaums is the ilium. I am in- 

 debted to Professor Phillips, and to the splendid collection of Megalosau- 

 rian remains which he has formed at Oxford, for most important evidence 

 touching this reptile. 



