138 couES, 



if any, obliquity, terminating at the broad oval cartilages of the floating 

 ribs, as high up, at least, as the lOtli from the last. 



Transversalis. — Larger and better defined than the last ; arising from 

 the whole lower margin of the thorax, internal to the oval cartilages, 

 by slips interdigitating with the diaphragm, from the xiphoid cartilage 

 to the last rib, and thence from the innermost lumbar fascial septum 

 (and so from transverse processes of vertebrse) to the apex of the 

 ilium. The muscle is thickest above, where some fibres reach quite 

 to the liuea alba, for 3-4 inches below the xiphoid ; further down these 

 cease at the linea semilunaris in the broad thin aponeurosis of median 

 insertion common to this muscle and the foregoing. All the muscular 

 fibres are directly transverse. 



Bectus abdominis (internus). — Is thoracic as well as abdominal — a 

 long continuous ribbon from episternum to pubes. It arises fleshy at a 

 point at the top of the thorax where epicoracoid, coracoid, episternum, 

 manubrium and first rib meet, taking attachment from all these bones, 

 and also slightly from the next rib as it passes down. On the thorax.it 

 rests a little on the sternum, but mostly lies- along the ends of the ribs, 

 overlaid by the pectoralis major, and crossed at bottom of the ster- 

 num by the obliquus abdominis (some of the fibres of which appear 

 to blend with the outer border of the rectus without I'eaching the 

 median line). The abdominal portion is a little wider and thinner, 

 in apposition with its felloW along the linea alba, separated from the 

 obliquus externus by interposition of the pyramidalis, and lying 

 wholly exterior to the conjoined aponeurosis of obliquus internus and 

 transversalis — these not forming a sheath below, as in man. The in- 

 sertion is into symphysis pubis and brim of that bone as far outward 

 as the termination of the articulation of the ossa marsupii. There are 

 no 'linese tendinese transversse.' 



Pyramidalis, s. Bectus externus. — Of great length ; and broad at base, 

 in consequence of the outward divergence of the marsupial bones, 

 from the whole length of which (their anterior border), and from the 

 symphysis, the muscle arises. The outer border represents a line 

 from the tip of the marsupial bones to the xiphoid ; the inner corre- 

 sponds to the linea alba. The lowermost fibres are almost directly 

 transverse; the others become successively less oblique to the axis 

 of the body, and finally are nearly longitudinal; the muscle runs to a 

 point above, and is fleshy throughout. It approximates and appresses 

 the marsupial bones, counteracting the obliquus externus, which divari- 

 cates them. It is thus in indirect subservience to the reproductive 

 process, in an early state of the young; and similarly, the thoracic 

 prolongation of the rectus internus furthers the bending of the animal 

 in voluntary self-assistance during parturition and subsequent care of 

 the j^oung, as in ordinai-y marsupials. 



