LIFE . AND KINSHIP OF DINOSAURS. C13 



absence of a tarsus, by the backward direction of the innermost or first toe (Fig. 16,0, as con- 

 trasted with the parallel position of that toe with the second toe in the reptilian foot (Fig. IG, 

 Scelidosaurus, Varanus). If the entire skeleton of an immature Chick, Ostrich, or Moa were 

 enlarged, whether suddenly or gradually, to the dimensions of that of a Cetiosaiu", and 

 were so ossified and fossilised, the characters of the dorsal vertebrije, of the cervical ver- 

 tebrae, of the skull, and the absence of an anterior pair of limbs with fore-paws organized 

 to be applied to the soil and take their share in the support and progression of a long 

 and bulky trunk and massive head as in the Dinosauria, would be decisive against the 

 reference of such imaginary gigantic Chick to any known representative of the Dinosaurian 

 order of Reptiles. But, to the Biologist who rejects the principle of adaptation of struc- 

 ture to function, the foregoing facts and conclusions will have no significance. 



By a modification of the hind-limbs the Bear, and by addition of a longer sacrum to 

 plantigrade feet the Ground-sloth, may assume a crouching bent-kneed attitude and hold 

 the fore-limbs free to grapple with a foe or a tree. 



Such is tlie plasticity of some mammalian structures that, by due training, a Bear, a 

 Dog, or a Monkey may be taught to dance and walk erect for a brief space. It may be 

 doubted whether a cold-blooded, small-brained Reptile could by any training be brought 

 to exemplify the mode of motion conceived in the quotation at p. 609, note t- But that, 

 like the Chlamydosaur with its long-toed, wide-spread, hind feet, the huge Dinosaurs 

 might assume the fighting posture of the Bear, when occasion called them to wield 

 their carpal weapons, is conceivable without commission of physiological or anatomical 

 solecism. 



The woodcuts, p. 603, Figs. 12, 13, 14,* give the pelvis and hind limb of a Moa [Dinornis) 

 and of a Crocodile {Crocodiliis) for comparison with the corresponding parts of a Dinosaur 

 {Omosaurus) : the position, proportions, and structure of the foot of which are guaranteed 

 by those of Ir/iianodon and Scelidosaurus. 



In the Crocodile the foot may be applied flat to the ground and the thigh turned out 

 nearly at right angles to the body ; but, in some phases of progressive motion, the limb 

 can assume the position delineated: the same may be predicated of the Dinosaurian 

 Reptile. The Bird occasionally rests on the foot, with the metatarsus flat to the ground : 

 but the thigh cannot be turned outward at the angle, which is possible in the Dinosaur 

 and Crocodile. When an accessory trochanter is present in the femur of a Dinosaur 

 {Iguanodon, Scelidosaurus), it projects from the inner border of the shaft, not from the 

 outer one, as in the restoration given in Fig. 3, p. 27, 'Quart. Journal Geo). Sec.,' 

 vol. xxvi, 1S70. 



* The letters have the same signification throughout ; U, ilium ; a, antacetabular plate ; I, post- 

 acetabular plate ; ib (in the Dinosaur) marks the superacelabular plate ; is, ischium ; pb, pubis ; /, femur 

 (of this only the lower part of the bone is given, so as not to conceal parts of the pelvis important in the 

 comparison); ;, tibia ; 6 or /J, fibula ; as, astragalus ; ca, calcaneum ; ci, cuboides ; ;", inner or first toe; 

 !i, second toe ; Hi, third toe ; iv, fourth toe ; v, rudiment of fifth toe. 



