VERTEBRATA. 61 



or but imperfectly shewn, in the previous preparations. The 

 greater part of the stomach and intestine has been removed, a 

 portion of the dilated rectum alone remaining. The heart, con- 

 sisting of two auricles and a ventricle, is seen in the mesial line 

 at the base of the throat. The carotid with its bulb-like carotid 

 gland and the lingual artery which it gives off, the systemic and 

 pulmonary trunks, into which the aortic bulb divides on each 

 side, are perhaps better seen. The same remark will also apply to 

 the left musculo-cutaneous vein, which is to be seen returning the 

 blood from the vascular and respiratory skin to the left superior 

 vena cava. On each side of the heart are the simple sac-like but 

 internally vesicular lungs. Below the heart are two lobes of the 

 liver, the third having been removed to shew the large gall- 

 bladder and the root of the epigastric vein. A little to the 

 right of the darkly stained gall-bladder is the globular spleen. 

 The two oval white bodies seen beneath the liver are the testes. 

 The vasa deferentia emerge from and pass through the substance 

 of the anterior part of the kidney, and finally open into the uro- 

 genital duct, which can be traced down the outer edge of the 

 latter organ. To the terminal part of each of these ducts is 

 appended a large lateral dilatation, the vesicula seminalis. The 

 large bifid allautois hangs down in front of the rectum. 



Division II. ALLANTOIDEA. 

 .Sub-division. SAUROPSIDA. 



Class AVES. 

 Order CARTNAT.E. 



9G. A Pigeon (Columba livia), dissected to shew the chief 

 features by which it differs from a Mammal. 



The roof of the cranial cavity has been removed and the brain 

 exposed. The right wall of the chest and abdomen has also been 

 removed. The origins of -the well-developed pectoralis major and 

 pectoralis minor muscles are to be seen along the edge of the 

 sternal keel. The skin has been removed from the front of 

 the throat, and the crop, after having been distended with spirit 

 and hardened, has been laid open and its cavity displayed. The 

 cerebral hemispheres are pear-shaped, with a smooth surface, 



