OF THE SOUTHERN APTERYX. 287 



ventral extremity of the pubis and from the inter-pubic Ugament : it soon becomes fleshy ; 

 the carneous portion is interrupted by three broad, oblique, but distinct aponeurotic in- 

 tersections (g*), and is finally inserted into the xiphoid and lateral processes of the ster- 

 num and the intervening fascia. 



Transversalis abdominis. — A layer of loose, dark-coloured cellular tissue divides the 

 internal oblique from the transverse abdominal, except at its origin from the pubis, and 

 for half an inch anterior to that part. 



The transversalis then proceeds to derive carneous fibres from the inner surface of the 

 vertebral ribs near their lower third ; they pass obliquely upwards and forwards, and 

 terminate by a regular, slightly concave line midway between their origins and the ex- 

 tremities of the ribs ; a strong aponeurosis passes thence to the linea alba, but becomes 

 thin at the pubic region, where a mass of fat is interposed between it and the peritoneum. 



Diaphragm (PI. XXXVI. & LII. Vol. ii.).— This muscle presents more of its normal 

 mammalian character in this than in any other known bird. It is perforated by vessels 

 only, in consequence of the non-development of the abdominal air-cells. The origin 

 corresponding to that of the lesser muscle in Mammalia is by two strong and distinct, 

 short tendinous pillars (a a), from the sides of the body of the last costal vertebra ; they 

 are united by a strong tendon or fascia, forming the anterior boundary of the aortic 

 passage. The tendinous pillars may be traced forward for some way in the central apo- 

 neurosis, expanding without crossing ; they are then lost in that aponeurosis, which is 

 perforated by the gastric arteries and veins ; decussates and divides anteriorly (at b) to 

 give passage to the gullet and the apex of the heart ; the aponeurosis expands over the 

 anterior part of the thoracic air-cells, and becomes, at its lateral circumference, the point 

 of attachment of muscular fibres arising from the inner surface of the anterior ribs, and 

 forming apparently a continuation of the transversalis abdominis. 



Appendico-costales (PI. XXXII. h).— Origin. From the posterior edge and extremity of 

 the costal processes or appendages. Ins. They run down to be inserted severally into the 

 rib posterior to that to which the process affording them origin is attached. These pro- 

 cesses are supported by strong triangular aponeuroses continued from their anterior and 

 upper margins, severally, to the rib anterior to them. 



The muscles of the jaws have already been described in the account of the digestive 

 organs'. The following are shown in PI. XXXII. : a, temporalis externus ; (3, temporalis 

 internus; y, biventer maxillcB ; the masseter has been removed, but is shown at;?. Pi. 

 XXXIV, fig. 1 . The internal pterygoid muscle is shown in PI. XXXV. at i ; the ex- 

 ternal pterygoid at ^. 



Some of the muscles of the tongue, which are described in the first part of this me- 

 moir\ are delineated in Plate XXXIV. fig. 1 . 



The strong orbicularis palpebrarum has been divided and reflected forwards at I, 

 PI. XXXII. ; it is shown in situ at S, fig. 1. PI. XXXIV. 



' Vol. ii. p. 26.3. s lb., p. 264. 



2q2 



