MUSCULATURE. 265 
this view is the fact that a similar division sometimes occurs in man, as pointed 
out by the same author. If this view be correct, the Echidna furnishes an 
interesting transition stage between the usual condition in which the latissimus 
is from the vertebral column, and that in the Proechidna in which the supple- 
mentary muscle, arising in the Echidna from the vertebral edge of the scapula 
close to the origin of the main muscle, has instead become shifted about two 
thirds the distance to the glenoid cavity to take origin from the low ridge at 
that point. An additional peculiarity of this supplementary portion of the 
latissimus in the Proechidna is that at its origin from the low ridge above the 
glenoid cavity it becomes split into two. One of the branches is that just 
described passing to the tendon of the latissimus; the second passes laterally 
as a flat band to its insertion along the ectal margin of the olecranon of 
the ulna. 
The serratus magnus is a large muscle, arising from the transverse processes 
of all but the first of the cervical vertebrae and from strips from each of the 
four most anterior ribs. It mserts along the vertebral edge of the medial side 
of the scapula, of which it covers practically the vertebral half. The longest 
of the digitations is that from the fourth rib, 388 mm. According to Westling, 
there is a digitation also from the fifth rib in the Echidna. 
The longissimus dorsi and the multifidus spinae are so intimately fused as 
hardly to be distinguished as separate muscles. The former arises as a thick 
flat muscle from the head of the ilium and its fibers pass forward to the spines 
of the lumbar and dorsal vertebrae. The multifidus spinae is a series of thin 
imbricated sheets arising by tendinous fibers from the tips of the transverse 
processes from the second lumbar vertebra forward. All are closely connected 
into a single mass that unites the transverse processes to the spines and adja- 
cent parts of the vertebrae, forward including the cervical vertebrae. 
What is evidently the homologue of the ilocostalis (Plate 1, fig. 1, ic) arises 
by a thin sheet of fascia from the head of the ilium and from the spines of the 
lumbar vertebrae. It passes obliquely forward as a band some 15 to 20 mm. 
wide, to about the fifth rib, and on the thorax breaks into a series of short mus- 
cular bundles each of which connects the external surface of two adjacent ribs. 
The splenius takes origin from very thin fascia covering the occiput and 
the neck as far back as the last cervical vertebra. At the midline the two 
muscles of opposite sides are continuous. 
The longissimus capitis is a thicker muscle than the last and arises from the 
lateral processes of the last four cervical vertebrae. These two muscles have 
