1905-6.] On Delphinus acutus from Coast of Sutherland. 315 
these measurements in the skulls of several species of dolphins 
in the University Museum : — 
Length of 
Skull. 
Length of 
Beak. 
Breadth of 
base of Beak. 
Delphinus acutus , . 
,, albirostris, 
,, delphis, . 
,, tursio, . 
14 -3 inches 
17 „ 
17*8 ,, 
21*5 „ 
7*1 inches 
8*5 „ 
11 *4 ,, 
11*25 ,, 
3 “8 inches 
5-8 „ 
3-8 „ 
5-9 „ 
It will be seen that in D. acutus , D. albirostris , and D. tursio 
the beak was about half the length of the entire skull, but in 
D. delphis the proportion of the beak to the length of the skull 
was materially greater. Although the skulls of albirostris and 
delphis were of almost the same length, the difference in the 
breadth of the base of the beak was 2 inches ; whilst acutus and 
delphis had the same breadth of beak, the skull of acutus was 
3 inches shorter; in D. tursio again, though the skull was 
4J inches longer than in albirostris, the beak had almost the 
same breadth at its base. D. acutus had not reached its full 
size, and possibly the proportions may be somewhat altered in 
the adult. 
Skeleton of Flipper. — The Scapula was plate-like ; the acromion 
was flattened and strongly projecting ; the spine was a slender 
ridge ; the prsespinous fossa was a narrow surface in comparison 
with the post-spinous. 
The Humerus, 2 inches long, was thick and stunted and the 
epiphyses were fused with the shaft. The Radius was 2'4 inches 
long and 1*5 inch broad ; the distal epiphysis was distinct from 
the shaft. The Ulna was 1*7 inch long and 1*1 inch broad; 
the distal epiphysis was distinct from the shaft and the olecranon 
process was moderate in size. 
The Manus consisted of carpus, metacarpus, and phalanges ; it 
was pentadaetylous. The carpalia were arranged in two rows. 
The proximal row consisted of radiale, intermedium and ulnare, 
and at the ulnar border a plate of cartilage represented an un- 
ossified pisiform. Two bones were readily recognised in 
the distal row ; one articulated with the carpal ends of the 
