691 
1908-9.] The Skeleton of a Sowerby’s Whale. 
region. The body was keeled on its ventral surface ; the transverse pro- 
cesses were spatulate and sprang from about the middle of the sides of the 
bodies ; the spines were long, flattened plates of bone. 
Caudal Vertebra . — Eighteen vertebrae followed the last lumbar. They 
diminished in size from before backwards ; the eight most posterior 
consisted only of a body, and that of the terminal vertebra measured only 
20 mm. in its antero-posterior and 18 mm. in its transverse diameter. 
The ten anterior had facets on the ventral surface for the nine chevron 
bones, which had articulated with them and with the intervertebral 
discs. 
Ribs . — There were ten pairs of ribs. The 1st and the 10th were the 
shortest; they increased in length from the 1st (32 cm.) to the 6th (62 cm.) 
and then diminished to the last (16 cm.). The 1st, the broadest and most 
flattened, had a facet on the head and one on the tubercle ; the right was 
marked by an oblique roughened groove on its surfaces, as if it had been 
fractured and afterwards repaired. The 2nd to the 7 th had also vertebral 
facets on the head and tubercle, but the 8th and 9th had no head and 
articulated only with a vertebral transverse process. The 10th was an 
elongated flat bone 30 mm. in greatest width, pointed at both ends, and 
without head and tubercle. 
The opportunity which I have had through the courtesy of Professor 
MTntosh of studying the skeleton of the St Andrews Mesoplodon has led me 
to re-examine the skeletons of the two Shetland and the Dalgety Bay animals 
and to reconsider the mode of articulation of the ribs with the spinal column. 
In each skeleton the head or capitular process of the 1st rib was jointed to 
the body of the 1st dorsal vertebra, the transverse process of which was so 
slender and pointed that the large articular facet on the tubercle of the rib 
could not be adapted to it. In approximating the 1st rib to the spine its 
tubercle came into contact with the transverse process of the 2nd dorsal, 
with which it obviously had articulated. It consequently followed that from 
the 1st to the 7th rib the tubercle articulated with the transverse process of 
the vertebra immediately behind the body to which the head was jointed, and 
with which it was in numerical correspondence. As the tubercle of the 7th 
rib therefore articulated with the transverse process of the 8th dorsal, the 
8th, 9th and 10th ribs, which had no capitular processes, articulated with 
the transverse processes of the 9th, 10th and 11th post-cervical vertebras. 
It required therefore eleven vertebrae to articulate with ten pairs of ribs. 
In the St Andrews skeleton the transverse processes of the 11th post- 
cervical vertebra were broken, but they were entire in the corresponding- 
vertebra in the other three skeletons, in each of which the free outer border 
