428 TRANSACTIONS OP SECTION D. 



pyramidal tract (which developed pari passu with the evolution of the neo- 

 pallium) ; and also with the cerebellum (by the simultaneous development of the 

 pons), which enabled the creature to co-ordinate the muscular activities of its 

 whole body to perform quick, accurately adjusted, and skilled movements. It is 

 such developments as these that made the mammals what we know them to be, 

 that give them their dominant position and their plasticity, or power of rapid 

 adjustment to varying environment. 



It is only when such skilled movements are possible that long limbs, capable 

 of supporting the body, can become useful appendages. The fact that such 

 limbs were making their appearance in the Therapsida in Triassic times is 

 tangible evidence of the birth of the neopallium in these Promammals. 



Professor Arthur Keith, Dr. C. W. Andrews, F.R.S., and Dr. Marett Tims 

 took part in the discussion. 1 



7. Note on the Manus of a Young Indian Elephant. 

 By Professor R. J. Anderson, M.D. 



The trapezoid is placed between the scaphoid, trapezium, second metacarpal, 

 and os magnum. The latter articulates with the second metacarpal and the third 

 articulates with the fourth and fifth. The base of the latter looks upwards and 

 outwards and backwards. The length of the trapezium is 6'5 cm. ; the breadth 

 4'5 cm. from side to side. This is much more like a metacarpal bone than are 

 the other bones of the carpus. The lower surface is convex from before back 

 and from within out. It reaches about halfway down the shaft of the second 

 metacarpal. The ' metacarpal ' of the first digit has both a proximal and distal 

 epiphysis. The proximal is 13 cm. thick and is quite separable in the skeleton, 

 so are the distal epiphyses of all the metacarpal bones. The thickness of the 

 lower (distal) epiphyses of the first metacarpal is 1"5 cm. One of the reasons 

 given for regarding the metacarpal of the thumb as such is the relation of the 

 bone to the carpus. Those who hold, or held, that this bone is a first phalanx, 

 point out the proximal epiphysis. In mammals other than man differences occur 

 in the number and arrangement of the epiphyses, as was pointed out long ago. 

 Graefenberg looks upon the trapezium as a metacarpal bone. Coalescence of the 

 carpal bones with adjacent bones is met with, not only in Carnivora, Insectivora 

 and others, and occasionally in man, but coalescence of the carpus and meta- 

 carpus occurs in man also. It is not easy to prove the permanent separation of 

 an epiphysial element as a normal act. One cannot find sufficient evidence for 

 regarding the proximal epiphysis as an epiphysis that properly belongs to the 

 trapezium, but became joined to the next bone of the ray in the course of 

 development. 



The metatarsal bone of the first toe (ray) has a proximal epiphysis. It is 

 difficult to say that a distal epiphysis is present. This is usually urged in favour 

 of regarding the bone as a phalanx. The internal cuneiform is long and articu- 

 lates with metas I and II. 



Professor Hans Virchow found in an Indian elephant, eighteen years old, 

 several terminal end-phalanges nnossified. The middle finger and middle toe 

 suffer more in this respect than the others, and the fingers less than the toes. 

 Sesamoid bones are formed in connection with the metacarpal- and metatarsal- 

 phalangeal articulations, two each for the three middle, one for metatarso- 

 phalangea I and for metacarpo-phalangea I. The fifth pair for the metacarpo- 

 phalangea V are united and look like the beginnings of a post-minimus digit. 



The flexor Carpi radialis helps perhaps to maintain the arch, but the liga- 

 ments, tendons, and sesamoids are more efficient. The tarsal movements are 

 slighter. The small radiale in the elephant and the large triquetrum contracts 

 with the large radiale and small triquetrum of Primates. The large manus and 

 their navicular are examples of vital readjustment. 



1 See Nature, December 28, 1911. 



