THE RABBIT 3*7 



To prepare the endoskeleton for study, open the abdominal cav- 

 ity, without injuring the sternum or ribs, and remove the viscera. 

 Cut away the diaphragm and remove the heart and lungs and other 

 thoracic organs. Remove the greater part of the muscles which 

 still remain in the body, being careful not to injure the bones. 



The body, thus prepared, should be boiled until the bones can 

 be thoroughly cleaned. It is well while doing this to disarticulate 

 the head and the hind limbs from the remainder of the skeleton. 

 Do not, however, boil the bones until they fall apart. It is also 

 well to pass a string through the neural canal as soon as the 

 spinal cord is destroyed, tie the two ends together so as not to lose 

 the sequence of the vertebrae, and number the ribs. 



The Appendicular Skeleton. The anterior extremities are made 

 up of the pectoral girdle and the forelegs. The pectoral girdle is 

 a paired structure which in most of the land vertebrates is made 

 up, on each side, of the scapula, coracoid, and procoracoid, or 

 clavicle. In the rabbit it is very incomplete, the dorsal element, 

 the scapula, being the only one which is well represented. This is 

 a flat, triangular bone which lies between the muscles and the ribs, 

 near the anterior end of the trunk, on each side. Projecting from 

 the middle of the outer surface is a flat ridge called the spine of 

 the scapula, which divides this surface into two areas : the supra- 

 spinous fossa, lying anterior to the spine, and the infraspinous 

 fossa, lying posterior to the spine. The ventral end of the spine 

 terminates in a projection, the acromion process, just above which 

 is a very long projection directed backward, called the metacro- 

 mion process. In the ventral end of the scapula is a depression 

 called the glenoid fossa, in which the humerus articulates. Near 

 the anterior end of this fossa is a curved projection, directed 

 laterally, called the coracoid process, which is homologous to the 

 coracoid bone of the lower vertebrates. 



Besides the scapula the pectoral girdle contains, on each side, 

 the clavicle. This is a small curved bone which lies embedded in 

 the muscles of the shoulder. It does not articulate with any other 

 bone, but is joined with the sternum medially, and with the hu- 

 merus laterally, by a ligament. 

 Exercise 39. Draw the lateral side of the scapula. 



