506 THE RABBIT CHAP. 



this muscle in the female are the mammary glands (p. 483), 

 which, when secreting, appear as whitish, branched masses, 

 the ducts of which can be traced to the teats, on the apices 

 of which they open by numerous small apertures. 



A whitish band of connective-tissue passes along the mid-ventral line 

 of the abdomen from the xiphisternum to the pubis : this separates two 

 longitudinal bands of muscle, the recti abdominis, from one another ; 

 and laterally to them, the abdominal wall consists of three thin layers 

 of muscle with their fibres running in different directions the external 

 obliqtie, the internal oblique, and the transversalis, the latter being 

 lined on its inner surface by the peritoneum. A fibrous cord, known as 

 Pouparfs ligament, beneath which the blood-vessels and nerves pass 

 outwards to the leg, extends upwards and forwards from each pubis 

 to the corresponding ilium. In the thorax the muscles of the body- 

 wall are broken up into separate portions by the ribs, and thus form a 

 series of intercostal muscles, which, like the oblique muscles of the 

 abdomen, are arranged in two layers, external and internal, and are 

 important in respiration. 



Extending from the thorax to the fore-limb of either side 

 are the \zxgepectoral muscles ; and a number of other muscles 

 can be seen in the neck, in the ventral middle line of which, 

 covered by the cutaneous muscle, the windpipe or trachea is 

 visible (Fig. 135). The trachea is strengthened by a series 

 of cartilaginous rings and ends in front in the larynx, situated 

 between the two rami of the mandible ; and just in 

 front of the larynx is the hyoid bone (p. 496), embedded 

 in a mass of muscle. 



The Coelome and its contents. On cutting open the 

 body-cavity, it will be seen to be divided into two main 

 chambers the thoracic and abdominal cavities by means of 

 the diaphragm (Fig. 135, d). The relatively small thorax 

 which is lined by a serous membrane corresponding to the 

 peritoneum of the abdomen and known as the pleura con- 

 tains the lungs, as well as the heart enclosed in a pericardium, 



