Mackintosh — On the Myology of the Genus Bradypus. 519 
into the upper part of the base of the scapula quite separate from it. 
The part corresponding to serratus magnus arises from the seven upper 
ribs, and is inserted into the whole length of the vertebral edge of the 
scapula. Professor Macalister gives its origin from the upper eight ribs, 
and its insertion into the lower two- thirds of the edge of the scapula; 
Meckel's description agrees with ours, whilst Professor Humphry- 
states that it is in two parts, the anterior extending from the first and 
second ribs to the superior angle of the scapula, and the posterior arising 
from the third to the eleventh ribs, and inserted into the under 
surface of the inferior angle of the scapula. 
Spleniusis described by Professor Macalister as " distinct, moderate 
in size, arising from the spines of the third, fourth, fifth, and sixth 
cervical vertebrae, and inserted into the transverse process of the atlas ; 
this part seems to correspond with the splenius capitis of other animals, 
but has no occipital attachment ; the second part, or splenius colli, arises 
from five spines below the last named muscle, and is inserted into the 
transverse processes of the second, third, fourth, and fifth cervical 
vertebrae." 
Complexus arises from all the cervical transverse processes, is 
inserted into the occipital bone, has no biventral portion and no ten- 
dinous intersections (Professor Macalister). 
Scalenus anticus arises from the third, fourth, fifth, and sixth cer- 
vical transverse processes, and is inserted into the first complete rib. 
Scalenus posticus arises from the corresponding processes of the sixth 
and seventh cervicals, and is inserted into the last cervical rib. The 
intercostal muscles extend from the last cervical to the first true rib. 
Semispinalis colli, longissimus dorsi, spinalis dorsi, ilio-costalis, 
musculus accessorius ad ilio-costalem, multifidus spinse, rectus capitis 
anticus major (origin, sixth, seventh, and eighth cervical vertebrae in 
Arctopithecus), rectus capitis posticus major and minor, obliquus capitis 
superior and inferior (the latter large in Arctopithecus), rectus capitis 
lateralis, longus colli (large in B. tridactylus), were all normal; rectus 
capitis anticus minor in Arctopithecus was made up of two parts, the 
inner smaller one from the first cervical, the other from the usual 
place, both had the normal insertion. The interspinales extend into 
the tail. 
Sterno-cleido-mastoid arises under the tendon of the pectoralis 
major, and is not mesially connivent in Arctopithecus, a condition 
found by Professor Macalister, who describes the origin from the front 
of the sternum, slightly from the first rib and very slightly from the 
inner end of the clavicle ; it is inserted by two slips into the paramas- 
toid process. It will be observed from this that the muscle is properly 
speaking a sterno-mastoid in Arctopithecus. 
Thyrohyoid, hyogiossus, and genioglossus, were all normal ; genio- 
hyoids were united in the middle line to form a single muscle in Arctopi- 
thecus ; sternohyoid and sternothyroid were united, the latter part 
being the largest and the origin broad in our specimen, separate and 
normal in B. tridactylus. Digastric univcntral, with a distinct in- 
