Chap. III.] GENERAL ANATOMY. 45 



Attention may now be drawn to some of the more salient 

 points in the general anatomy of the rabbit : 



1. The lungs are contained in separate pleural sacs, and these, 

 together with the pericardial sac, are contained within the 

 thoracic cavity, which is well marked off from the peritoneal 

 cavity. The coelom is thus sub-divided. 



2. There is a complete diaphragm behind the lungs. 



3. The heart has two ventricles and two auricles ; there is no 

 separate sinus venosus or truncus arteriosus. 



4. There is one aortic arch, the left. 



5. There is no renal portal vein distributing blood from the 

 posterior regions to the kidney. 



6. There are separate ducts for the testis and the kidney in 

 the male. 



7. There is no cloaca. The urino-genital aperture being dis- 

 tinct from the anus. 



8. The urinary bladder receives the ureters and opens into a 

 nrino-genital canal. 



4. The Pigeon. After plucking the ventral aspect of the 

 pigeon, tie a piece of fine string round the beak at the base of 

 the cere, insert the blow-pipe into the mouth, and tighten the 

 string. Then inflate until the crop and abdomen are moderately 

 distended, and withdraw the blow-pipe, tightening and knotting 

 the string so as to prevent the escape of air. Place the bird on 

 its back, and make a median incision in the skin from beak to 

 cloaca. Eeflect the skin and make out the structures already 

 visible in the neck. The soft thin-walled gullet or oesophagus is 

 seen to expand into a large bi-lobed crop. Over it anteriorly lies 

 the ringed trachea, which passes to the left, and so over to the 

 dorsal side of the crop (Fig. 20, Tr.). Behind the crop, in its 

 present position, lie the jugular veins gorged with blood, and 

 connected with ramifying plexuses of blood-vessels in the skin of 

 the neck. A stout nerve (the vagus) accompanies each jugular. 

 Paired oval reddish lymphatic glands will also be visible in the 

 neck. 



Make an incision in the abdominal walls from the posterior 



