REPORT ON THE SEALS. 233 



is inserted into the occipital bone posterior to the insertion of the complexus, and between the 

 superior oblicpae and the rectus capitis posticus minor. 



The Rectus capitis posticus minor in Phoca vitidina is nearly rectangular, and its anterior end 

 is the broader. It arises from the tubercle on the tip of the neural arch of the atlas, and from the 

 thin dorsal surface of its lamina anterior to the foramen. It ascends, and is inserted into the 

 whole of the surface of the occipital bone, behind the insertion of tne major rectus accessorius in 

 front of the foramen magnum, and as far out as the inner side of the condyle of the occipital bone. 

 This insertion is extensive. It is supplied by the suboccipital nerve. 



In Arctoeephalus it arises from the anterior dorsal half of the atlas, between the neural spine and 

 its foramen and the articular surface for the occipital condyle. It is inserted into the supraoccipital 

 bone, posterior to the biventer cervicis internally, and the rectus capitis anticus major externally. 

 It is bounded by the rectus capitis posticus and the complexus, and posteriorly by the foramen 

 magnum. 



The OUiquus capitis inferior in Phoca vitidina is a short rectangular muscle, and arises from the 

 side of the neural spine of the axis beneath the major and accessorius muscles, from the whole of 

 the dorsal surface of its lamina, and slightly from the dorsal surface of the posterior zygapophysis 

 of this vertebra. It passes outwards and forwards, and is inserted into the concave posterior surface 

 of the transverse process of the atlas ventral to its foramina. It is supplied by the suboccipital and 

 the great occipital nerves. 



In Arctoeephalus it arises from the outer side of the neural spine of the axis, and the dorsal 

 surface of the lamina to the inner side of the hyperapophysis. It is inserted into the concave sur- 

 face on the posterior dorsal half of the wing-like transverse process of the atlas. 



The Obliquus capitis superior in Phoca vitidina is the same shape as the last ; it arises from the 

 dorsal anterior surface of the condyle of the atlas, and from the dorsal edge of the transverse pro- 

 cess of the same. It is inserted into the middle of the occipital ridge between the rectus capitis 

 posticus major, and the rectus lateralis beneath the complexus. It is supplied by the suboccipital 

 nerve. 



In Arctoeephalus it arises from the anterior surface of the atlas outside the foramen, and is 

 inserted into the lower half of the occipital ridge, into the upper half of the paramastoid process, 

 and the exoccipital bone. 



The Muscles of the Tail. 



I have only observed one muscle arising from the caudal region in Phoca and in Arctoeephalus. 

 This is named in the text of Lucae the abductor caudae, while Murie calls it the levator caudaa 

 externus. The levator caudas of Lucae, and the levator caudse internus of Murie, are simply prolon- 

 gations backwards of the erector muscles of the back into the caudal region, and are described as 

 part of these muscles. The ventrales caudae of Lucae are the same as the pubo-, ilio-, sacro-, and 

 infra-coccygeus of Murie, and are included in my description of the levator ani. 



The Abductor caudse in Phoca vitidina arises from the dorsal surface of the dorsal sacro-iliac 

 ligament, and from the under surface of the transverse processes of all the sacral vertebra?, and is 

 inserted into the same parts of the caudal vertebrae. It is supplied by the caudal nerves. 



In Arctoeephalus it arises from the dorsal anterior spine of the ilium, from the dorsal surface of 



(ZOOL. CHALL. EXP. — PART LXVIII. — 1888.) Yyy 30 



