410 DR MORRISON WATSON AND MR ALFRED H. YOUNG 
Sterno-hyoid Muscle.—Origin cut. The muscle is broad, flat, of great strength, 
and is inserted partly into a well-marked transverse ridge on the lower surface 
of the basi-hyal, but chiefly into the whole length of the thyro-hyal bone. It 
rests by its deeper surface on the sterno-thyroid and thyro-hyoid muscles. 
In Globiocephalus* the muscle is similarly arranged, whilst in Balenoptera 
rostrata t its insertion is limited to the basi-hyal bone. 
Sterno-thyroid Muscle.—Origin cut. It is inserted into an oblique ridge on 
the outer surface of the thyroid cartilage, much as in the human subject. 
In Globiocephalus{ the muscle agrees exactly with this description. In 
Balenoptera rostrata § it is absent. 
Thyro-hyoid Muscle is very strong. It arises from the oblique line above 
mentioned, of the thyroid cartilage. The fibres diverge as they pass forward, and 
are inserted into the whole length of the thyro-hyal as well as into the posterior 
border of the basi-hyal bone. The muscles of opposite sides are in contact at 
their origins, but diverge so as to leave an interval at their insertion. 
In Globiocephalus, MACALISTER || observes that the muscle is inserted into the 
basi-hyal bone alone, whilst in Balewnoptera rostrata I its insertion is confined to 
the thyro-hyal. 
Mylo-hyoid Muscle is broad and powerful. Its fibres arise from the whole 
length of the thyro-hyal bone, and pass forward toward the lower jaw, into which 
in all probability they are inserted. Unfortunately, the insertion had been cut 
before the specimen reached us. Its fibres are not transverse, as described by 
Dr Muriz ** in Globiocephalus, but longitudinal in direction. 
Carte and MacatisTER tt describe the muscles of opposite sides as blending 
along the middle line in Balcenopiera. Such is not the case in Beluga. 
Genio-hyoid Muscle, broad and flat, consists of a single fleshy mass occupying 
the middle line of the lower jaw from the symphysis to the hyoid bone. It 
arises from the transverse ridge on the lower surface of the basi-hyal bone by 
means of a flattened tendon, and passes horizontally forward toward the lower 
jaw. Its insertion was cut, but a comparison of the parts with Dr Murin’s tt 
drawing of those in Globiocephalus leaves little doubt that in Beluga the 
muscle is inserted exactly as in the Bottle-nose. 
Genio-glossus Muscle.—The origin of this muscle was unfortunately divided, 
but the relative position and direction of its fibres appeared to indicate that it 
represented the genial fibres of the genio-hyo-glossus of other mammals, and 
that consequently it arose from the posterior aspect of the symphysis of the 
lower jaw. The fibres pass upward, and radiating as in the human subject are 
inserted into the under surface of the tongue from an inch behind the tip as far 
back as the cartilaginous cerato-hyals. 
* IL p. 268. tL pace, t IL. p. 263. § 
\| VL p. 480. { L. p. 219. ** TT, p, 251. r 
tt IT. plate xxxi. fig. 11. 
