8 H. W. MARETT TIMS. 
TABLE ITI. 
CoMPARISON OF Limp MEASUREMENTS OF SPECIMENS IN THE ‘BELGICA’ AND 
‘“DIscovERY ’ COLLECTIONS. 
‘Betagica’ MarERIAL. ‘DISCOVERY’ MATERIAL. 
Body length. ee ee at, Ratios. Body length. Goaee an - Ratios. 
113 H. 8 7°08 114 H. 9°5 8°3 
F. 9 7°96 F. 10°0 8°7 
120 H. 10 8°33 121 H. 12°5 10°3 
F.. 12 10°00 F. 13°0 10°7 
172 H. 18 10°46 : ‘ : 
F. 19 11°04 No specimens of corresponding size. 
190 H. 20 10°53 190 H. 18°5 9°7 
F. 28 12°10 F. 21°0 7 11°0 
The following conclusions arrived at by Professor Leboueq from his four 
specimens are fully borne out by the study of this additional material, viz. :— 
1. The length of the limbs does not remain of constant proportion to that 
of the body. 
2. The proportion per cent. increases from the earlier to the later stages. 
3. The increase in the hand and foot does not remain parallel, but is in favour 
of the foot. 
And further the surmise that, in stages younger than those in his possession, the 
proportions of the two extremities would be equal, is shown to be correct by the 
younger embryos of the ‘ Discovery ’ collection. 
The limbs appear as buds, with bulbous extremities, which spring out almost at 
a right augle to the long axis of the trunk (fig. 1) with the flexor surface apposed to 
the body, the radial and tibial borders directed anteriorly, and the median axes 
of the arm and leg directly continuous with those of the manus and pes. This 
continuity of the axis persists from a short time after the appearance of the digits 
(fig. 4). Very soon, however, the manus becomes ulnar flexed, so that the median axis 
of the hand forms an obtuse angle with that of the arm, the radial border of the 
forearm being in a direct line with the radial border of the pollex (fig. 5). Up to this 
point the change in position seems to have affected the hand only, but now the whole 
limb begins to assume a backward direction, the axes of the hand and arm once more 
become almost continuous (figs. 6, 7). In*the case of the hind limb the backward 
extension is gradual but continuous, the movement affecting the whole extremity 
simultaneously. 
