OF THE SOUTHERN APTERYX. 281 



humerus in the Apteryx, the true muscles of the back, whicli correspond to the second 

 layer of the dorsal muscles in Man, become immediately visible on removing the dorsal 

 integuments and fasciae ; they consist of the sacro-lurabalis, lovgissimus dorsi, and spinalifi 

 dorsi. The first two muscles are blended together at their posterior origins, but soon 

 assume the disposition characteristic of each as they advance forwards. 



The sacro-lumbalis (PI. XXXII. XXXIII. /) is a strong and fleshy muscle, six lines in 

 breadth, and three or four lines in thickness : it is, as usual, the most external or lateral 

 of the muscles of the back, and extends from the anterior border of the ilium to the penulti- 

 mate cervical vertebra. Origin. By short tendinous and carneous fibres from the outer 

 half of the anterior margin of the ilium, and by a succession of long, strong, and flat- 

 tened tendons (PI. XXXIII. fig. 2. 1 1-Z 5) from the angles of the fifth and fourth ribs, and 

 from the extremities of the transverse processes of the third, second, and first dorsal ver- 

 tebrae ; also by a shorter tendon (/ 6) from the transverse process of the last cervical 

 vertebra ; these latter origins represent the musculi accessorii ad sacro-lumbalem ; to bring 

 them into view, the external margin of the sacro-lumbalis must be raised, as in PI. XXXIII. 

 fig. 2. These accessory tendons run obliquely forward, expanding as they proceed, and 

 are lost in the under surface of the muscle. 



Insertion. By a fleshy fasciculus with very short tendinous fibres into the angle of the 

 sixth rib, and by a series of corresponding fasciculi, which become progressively longer 

 and more tendinous, into the angles of the fifth, fourth, third and second ribs (PI. XXXII. 

 /*), and into the lower transverse processes of the first dorsal and last two cervical ver- 

 tebrae : the last insertion is fleshy and strong ; the four anterior of these insertions are 

 concealed by the upper and outer fleshy portions of the sacro-lumbalis, which divides 

 into five elongated fleshy bundles (PI. XXXII. I**), inserted successively into the upper 

 transverse processes of the first three dorsal and last two cervical vertebrae. These 

 last insertions seem to represent the continuation of the sacro-lumbalis iu Man, which 

 is termed the cervicalis descendens or ascendens. 



Longissimus dorsi (PI. XXXII. XXXIII. m). — This muscle is blended posteriorly both 

 with the sacro-lumbalis and the multijidus spinte, and anteriorly with the outer portion of 

 the spinalis dorsi. It extends as far forward as the thirteenth cervical vertebrae. Origin. 

 From the inner or mesial half of the anterior margin of the ilium ; from a strong apo- 

 neurosis attached to the spines of the eighth, seventh and sixth dorsal vertebrae ; and from 

 the transverse processes of the sixth, fifth, fourth and third dorsal vertebrae. 7ns. The 

 carneous fibres continued from the second origin, or series of origins from the spinous 

 processes, incline slightly outward as they pass forward, and are inserted into the poste- 

 rior articular processes of the first three dorsal vertebrae, receiving accessory fibres from 

 the spinalis dorsi. The fasciculi from the transverse processes incline inwards, and are 

 also inserted into the posterior oblique processes of the vertebrae anterior to them ; they 

 receive fibres from the iliac origin, and soon begin to form a series of oblique carneous 

 fasciculi, which become more distinct as they are situated more anteriorly ; they are at 



