316 Proceedings of Royal Society of Edinburgh. [sess. 
metacarpals of annularis and medius, another with the carpal 
ends of the metacarpals of medius and index. A third hone was 
situated distal to the radiale, and close to the radial border of the 
proximal epiphysis of the metacarpal of the index. The question 
arose, Could this be the metacarpal of the pollex? hut as it was 
in the same transverse plane as the distal carpalia, and, like the 
other carpals, showed no sign of an epiphysis, it was presumably 
a third distal carpal, and represented the carpal element of the 
pollex. 
Each digit had its metacarpal bone. That of the pollex was in 
the same transverse plane as the shaft of the other metacarpals ; it 
was slender and elongated, with a cartilaginous prolongation at both 
its proximal and distal ends ; there was no sign in the cartilaginous 
Tig. 4. — Radiograph of the flipper of I). acutus, showing the bones and the 
centres of ossification, reduced to about one-third. 
prolongation of an epiphysis or a centre of ossification which 
nould be regarded as even the rudiment of a bony phalanx. The 
index was the longest of the digits, and they diminished in length 
from it to the minimus ; each of these four had a metacarpal bone, 
which possessed in the index, medius and annularis a proximal 
and a distal epiphysis, whilst in the minimus only a proximal 
epiphysis had a centre of ossification. 
The index had eight phalanges, three of which had proximal 
and distal epiphyses ; the fourth had only a proximal, and the ter- 
minal four each showed only a small ossific centre without epiphyses. 
The medius had five phalanges, of which two had proximal and 
distal epiphyses, and the third had a faint trace of a proximal. The 
annularis had an ossific centre for each of three phalanges in the right 
manus but only two in the left. The minimus had a cartilaginous 
