218 THE VOYAGE OF H.M.S. CHALLENGER. 



posterior arises from the bodies of the 1st to the 7th dorsal vertebrce, from the intervertebral discs, 

 from the ventral surfaces of the rib joints, and from the body of the last cervical vertebra. It 

 ascends and lies to the outer side of the rectus capitis anticus major, and is inserted into the 

 ventral divisions of the cervical transverse processes of the 2nd to the 6th cervical vertebra;, to the 

 outer side of the origins of the rectus capitis anticus major. The anterior part arises from the 

 inner sides of the ventral divisions of the transverse processes of the 3rd to the 6th cervical 

 vertebra;, the origins from the anterior ends being tendinous. It lies to the inner side of the 

 rectus capitis anticus major, and is inserted into the bodies and intervertebral discs of the vertebra; 

 reaching to the atlas, the fibres from the 6th going to the 5th, from the 4th to the 3rd, from the 3rd 

 to the 2nd and 1st cervical vertebra;. It is supplied by branches of the brachial plexus. 



In Arctocephalus there are three parts. The posterior oblique arises from the bodies of the 1st 

 to the 4th dorsal vertebra?, from the intervertebral discs, from the ventral surfaces of the rib 

 joints, and from the body of the last cervical vertebra; and is inserted into the outer side of the 

 ventral division of the 6th cervical vertebra. The anterior oblique lies on the outer side of the 

 rectus capitis anticus major, and arises from the outer sides of the ventral divisions of the transverse 

 processes of the 3rd, 4th, 5th, and 6th cervical vertebra; ; and is inserted by three slips into the 

 dorsal tubercles of the 3rd, 4th, and 5th cervical vertebra;, and the outer half of the ventral surface 

 of the wing of the atlas. The vertical part arises from the inner surface of the ventral divisions 

 of the transverse processes of the 2nd to the 6th cervical vertebra;. The fibres go forwards, and are 

 inserted into the hypapophyses of the 2nd to the 6th cervical vertebrse. 



In Otaria and Trichechus Dr. Murie describes two parts. 



The Lateral Vertebral Region includes three muscles in Phoca vitulina — the scalenus 

 anticus, medius, and posticus. In Arctocephalus the scalenus medius is wanting. 



The Scalenus anticus in Phoca vitulina is a short band of muscle, and arises from the anterior 

 and outer surface of the 1st rib at its junction with its cartilage, and proceeds forwards to be inserted 

 into the antero-posteriorly elongated hatchet-shaped ventral divisions of the transverse processes of 

 the 4th and 5th cervical vertebra; by tendinous slips. A fasciculus from it blends with the tendon 

 of insertion of the scalenus medius into the 3rd cervical. It is supplied by the branches of the 

 brachial plexus. 



In Arctocephalus it lies between the longus colli ventrally and the serratus posticus dorsally. It 

 arises from the anterior border of the 3rd rib, anterior to the origin of the digitation of the serratus, 

 from the same border of the 2nd and 1st ribs, but to the inner side of the digitations of the 

 serratus. The muscle forms a flattened band, and is inserted into the tip of the ventral division of the 

 transverse process of the 7th cervical, and into the ventral sides of the dorsal divisions of the 

 transverse processes of the 3rd, 4th, 5th, and 6th cervical vertebrse. 



The Scalenus medius in Phoca vitulina is larger than the last, and arises from the anterior 

 triangular surface of the 1st rib near its vertebral end, lying behind and a little to the outer side 

 of the anticus. It is inserted by a tendon into the ventral hatchet-shaped division of the 4th cervical 

 vertebra, by a fasciculus into the under surface of the tendon of the posticus going to the 4th 

 cervical vertebra, and into the posterior surface of the tendon of the same muscle going to the 

 3rd cervical vertebra by the same fasciculus, which is continued forwards from behind the tendon 

 of the posticus to the 4th vertebra. In the large Phoca vitulina the muscular arrangement 



