178 DR. J. MURTE ON THE FORM AND STRUCTURE OF THE MANATEE. 
verge below the parotid gland and join the external jugular opposite the paramastoid. 
The brachio-cephalic vein comes inwards from above the insertion of the pectoralis 
minor; and another marked tributary is derived from the vascular plexus covering the 
inner subscapular region. 
The course of the external jugular vein is from behind the cranial end of the stylo- 
hyal and the thereupon attached portion of the digastric muscle, backwards and slightly 
obliquely outwards, uniting with the internal jugular near the first rib. The external 
almost equals the internal jugular vein in calibre; and it lies over the tendon of the 
sterno-mastoid muscle and the suprascapular artery. 
The internal jugular vein commences at the cranial aperture, foramen lacerum 
posterius, near to the attachment of the rectus lateralis and cephalo-humeral muscles, 
where there is a large venous plexus as in Cetacea. As it traverses the neck backwards 
it lies chiefly to the inner side of the carotid artery, crossing it, however, about the 
level of the bifurcation of the trachea, posterior to which it converges to the large 
innominate trunk formed by it, the external jugular, and the subclavian vein. There 
are several oblique bridging communications between the ecto- and entojugular veins. 
No valves were observed in the above veins of the neck. 
The deep cervical glands are very voluminous, and fill the intervening cleft, bounded 
anteriorly by the cephalo-humeral muscle, externally by the subscapularis, deeply or 
dorsally by the short neck-muscles, the lateralis and obliquus externus, and within or 
mesially by the extension forwards of the serratus magnus. The cervical plexus of 
nerves passes over the glands in question, the latter being enveloped amidst the rete 
mirabile. 
VII. VocaL anp Resprratory APPARATUS. 
1. The Air-passages. 
Stannius has been successful in his exposition of the structure of the larynx. I may 
refer, however, to two points he and Rapp have failed to notice, viz. the existence of a 
small recess or pseudo-sacculus laryngis at the anterior extremity of the vocal cord, as 
in the Dugong; and to the presence of small nodular cornicula laryngis or cartilages of 
Santorini, surmounting the arytenoid bodies. As these authors and Vrolik state, the 
epiglottis, unlike the Cetacean, is of the most rudimentary character; the thyroid car- 
tilages are united anteriorly by a narrow bridge, and anterior and posterior cornua are 
well developed; the cricoid is a complete ring posteriorly, very broad, and with a 
marked prominence for the attachment of the thyroidal posterior cornu; the arytenoids 
are trihedral; the vocal cords are the reverse of prominent, and deficient in inferior 
excayation. ‘The several ligaments are composed of tough yellow and fibro-elastic 
tissues; and the diminutive epiglottis, curiously enough, consists of like material, void 
of a cartilage basis. 
The dozen tracheal rings, and, as far as I could make out, the bronchial also, are not 
