REPORT ON THE SEALS. 215 



hyoid by Humphry, and the sterno-hyoid and sternothyroid by Murie. It is a long band with a 

 triangular expansion from its outer side opposite the head of the humerus, the apex lying upon it. 

 It is situated along the side of the neck upon the carotid artery and pneumogastric nerve, &c, and 

 arises by muscular fibres from the outer surface of the cartilage of the 1st rib, from the outer 

 surface of the lesser tuberosity of the humerus, from the transverse ligament going between the 

 two tubers of the humerus, and from the fascia binding together the great vessels and nerves going 

 to the nipper from the thorax and stretching from the 1st rib to the lesser tuber. At the level of 

 the thyroid gland it splits into two parts, an anterior and a posterior. The deeper or posterior is 

 inserted into the thyroid cartilage, the superficial or anterior into the hyoid bone ; in the large 

 specimen, the division was about midway between the origin and insertion. The part from the 

 lesser tuberosity may be named the omo-hyoid. It is supplied by the communicans noni nerve. 



In Arctocephalus it arises from the tip of the dorsal surface of the presternum, proceeds for- 

 wards, and about 1 inch posterior to the thyroid cartilage divides into a dorsal and ventral band. 

 The dorsal is the sterno-thyroid, and is inserted into the thyroid cartilage, the ventral is the sterno- 

 hyoid and is inserted into the hyoid bone. The nerve was destroyed. 



The Omo-hyoid in Plioca vitulina is the part of the sterno-thyro-hyoid attached to the humerus, 

 in Arctocephalus it is the outer margin of the sterno-mastoid. The Sterno-thyro-hyoid in Arcto- 

 cephalus has an origin somewhat like the sterno-mastoid in Plioca. Humphry does not refer to the 

 part forming the sterno-hyoid. 



The Thyro-hyoid in Phoca vitulina and in Arctocephalus arises from the posterior part of the 

 oblique ridge of the thyroid cartilage, and is inserted into the hyoid bone. 



The Supra-hyoid Region. — In this region are the digastric, stylo-hyoid, mylo-hyoid, and genio- 

 hyoid. 



The Digastric in Phoca vitulina and Arctocephalus arises from the mastoid hollow and the 

 tympanic bulla. About its middle, in Phoca, a superficial transverse tendinous division exists. It 

 is inserted into the inferior surface of the angle and inferior border of the lower jaw to opposite the 

 last molar tooth on the inner surface. It is supplied by the facial and by the mylo-hyoid branch of 

 the inferior dental nerve. 



In Otaria there is no tendinous intersection, but it is present in Trichcchus. 



The Stylo-hyoid in Phoca vitulina and Arctocephalus is a narrow transverse band, and arises 

 from below the external auditory meatus, and is inserted into the hyoid bone. Humphry 

 considers it to be a part of the digastric, and Murie does not describe it. It is supplied by the 

 facial nerve. 



The Mylo-hyoid in Phoca vitulina- and Arctocephalus is a triangular muscle, which, with its fellow, 

 fills in the intermaxillary space. It arises from the inner surface of the lower jaw above and a 

 little behind the inferior dental foramen, and from the alveolar margin until opposite the last molar 

 tooth, where the line of origin turns suddenly to reach the inferior border of the lower jaw. Thus 

 far the origin is muscular, but at the symphysis it is tendinous. The fibres are inserted into a 

 median fibrous raphe" and into the body of the hyoid bone. The digastric intervenes between it 

 and the lower jaw at the angle. It is supplied by the mylo-hyoid branch of the inferior dental 

 nerve. 



The Gcnio-hyoid in Phoca vitulina and Arctocephalus is a small rectangular muscle situated 



