364 Rev. H. N. Hutchinson — Observations on 



turtle), however, shows only an imperfect kind of head, not nearly 

 a complete sphere. So with the humerus. Tortoises are highly 

 specialized reptiles ; and this contrivance is doubtless a very 

 necessary one on account of the weight of the carapace, for without 

 it the limbs could not perform their proper functions. 



Dr. W. J. Holland and some others have been so bold as to place 

 the femur right inside the creature's body, and in that way we 

 presume they attempt to get out of the difficulty above referred to. 

 But the result is certainly strange, causing Diplodocus to remind one of 

 a cow rather than a reptile ! (see Dr. Holland's model above referred 

 to). Besides, the whole shape of the pelvic girdle militates against 

 any such interpretation. If the femur really worked in the way 

 suggested by Holland and others, the writer believes that a different 

 shape of ilium would be necessary, viz. one more on the lines of 

 a mammal, that is, more outspreading. 



It is very instructive to compare the hind-limb of Diplodocus and 

 Triceratops. Fortunately both these colossal Dinosaurs are exhibited 

 in the same gallery at the Natural History Museum. Consequently 

 the comparison is easily and rapidly made. Now' the hind-limb of 

 Triceratops (see the writer's Extinct Monsters and Creatures of Other 

 Days, now in one vol., 1911, p. 182), owing to its rather upright 

 position, and the ponderous nature of this Dinosaur (which probably 

 possessed a heavy dermal armour, at least in the writer's opinion), 

 had to support a great weight. Hence the three ungual phalanges 

 are decidedly broad — more so than in any other known Dinosaur. 1 

 And, moreover, that outward twist, so noticeable in Diplodocus, is 

 entirely absent. These and other features confirm a suggestion of 

 the writer that Triceratops may claim to be regarded as a reptile that 

 years ago played the part of a rhinoceros, i.e. foreshadowing in an 

 imperfect reptilian way that great and ferocious mammal ! The 

 rather sharp and distinctly claw -like ungual phalanges of Diplodocus 

 bear their testimony in favour of the interpretation of the skeleton 

 adopted in this paper ; for with the hind-limbs set up in the vertical 

 plane (as in the American reconstruction) (PI. XXII), the downward 

 pressure brought to bear upon them would be so excessive that they 

 would probably break, or if not, they would be pressed so deep 

 into sand or soft earth as greatly to hinder progression on land. By 

 way of illustration, and to show that this conclusion is based on 

 reasonable grounds, let us take the case of a large dog, say a mastiff. 

 Leave his limbs almost as they are, but give him a heavy body with 

 a great massive vertebra and a long weighty tail ; and then 

 endeavour to picture his distress in propelling along the ground this 

 mass of bone and flesh (even allowing for certain corresponding 

 increase in strength of limb) ! The weight of his body would be felt 

 as direct downward pressure through the limbs and on to the toes. 

 But place the limbs at an angle to the body, and this great 

 pressure is relieved, because the femur — with the tibia and fibula, 

 with the muscles attached to them — act as a kind of spring, set 

 sideways to the body (see Pig. 3, p. 362). 



1 Compare with foot of Elephas. 



