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 oiigin horn 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 cer\-ical Vertebrae and from strips from each of the 

 four most anterior ril)s'. It inserts along the \'ertebral 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, 38 nun. 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 \'ertebrae. 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 iliocostalis (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 longissi^nus capitis is a thicker muscle than the last and arises from the 

 lateral processes of the last four cervical vertebrae. These two muscles have 



