Aperture by which the left auricle joins the ventricle.
Each auricle forms the terminal enlargement of the efferent vein of the ctenidium of its own side.
The oxygenated blood is carried from each gill by an efferent vessel on the external or pallial side of the axis to another longitudinal vessel which leads to the auricle on each side.
X, Auricle of the heart.
The afferent vessel of the' ctenidium receives blood from the vena cava or principal blood-sinus of the body, the efferent vessel opens into the auricle of its own side.
A form of contraction intermediate in character between the tonic and the rhythmic is met in the auricle of the heart of the toad.
The heart c lying in the pericardium is seen in close proximity to the renal organ, and consists of a single auricle receiving blood from the gill, and of a single ventricle which pumps it through the body by an anterior and posterior aorta.
When the pericardium is cut open from above in an animal otherwise entire, the anterior face of the kidney is seen forming the posterior wall of the pericardial chamber; on the deep edge of this face, a little to the left of the attachment of the auricle to the floor of the pericardium, is seen a depression; this depression contains the opening from the pericardium into the kidney.
Six or seven species of mosquitoes are also the intermediate hosts of Filaria immitis, which infests the right auricle and pulmonary artery of the dog, and occurs throughout the tropics, in southern Europe, the United States of America, and elsewhere.
In the majority of Gastropoda one gill and one auricle are lost.