582 PROF. OWEN ON HYPSIPRYMNODON. 



In these ponderous slow-moving quadrupeds the exercise of the muscles and con- 

 comitant vigour of circulation and innervation in locomotion was inferior to those 

 affecting the main instrument in the swift course of the Horse and Kangaroo; the 

 claw-bearing toe mainly (if not exclusively) exercised in exposing the ramifications of the 

 root of the tree to be felled, was the subject of those influences which govern excessive 

 or exclusive development. 



In conclusion, I may remark that the longest and strongest toe in the pentadactyle 

 hind foot of the Lizards is the fourth ; and I deem it indicative of the nearness to 

 Saurians of the Implacentalia among mammals — an affinity so remarkably shown by 

 monotremes in other parts of the skeleton — that in the progressive reduction of the foot 

 in Marsupials the fourth toe, iv, holds the preeminence. 



In the march of Man the chief motive power is concentrated on the innermost toe 

 (i) as the main instrument, thence called the " hallux," or " great toe." In this modi- 

 fication of the foot for bipedal station and locomotion the human kind stands alone in 

 the animal kingdom. 



DESCRIPTION OF THE PLATES. 



Plate LXXI. 



Figs. 1 & 2. Hypsiprymnodon moschatus, Ramsay : nat. size. 1, male ; 2, female. 



Plate LXXII. 



Fig. 1. Side view of the skull of Hypsiprymnodon moschatus, Rms. 



2. Upper view of the same. 



3. Under view of the same, i 1, 2, 3, incisors; c, canine; p 3, premolar; d4>, milk- 



molar; m 1, 2, 3, molars. 



4. Upper view of the mandible of the same. Letters as in fig. 3. 



5. Bones of the forearm and paw of the same, i, n, in, iv, v, digits. 



6. Bones of the hind foot : e, entocuneiform ; i to v, digits. 



7. The same, from the opposite (plantar) side. 



8. Mandible of Hypsiprymnus Gilberti : c, canine ; p 3, premolar ; d 4, milk -molar ; m 1, 2, 3, 



molars. 



9. Bones of forearm and paw of the same, i to v, digits. 



10. Bones of the hind foot, plantar aspect, of the same : ii to v, digits. All the above 



figures are of the natural size. 



11. Bones of the foot of Apteryx. 



12. The same bones of the Cassowary {Casuarius). 



13. The same of the Ostrich (Struthio). The same letters are applicable to these three 



figures, viz. e, epiphysis; 2, 3, 4, metatarsals ; i, n, m, iv, digits. 



