Aperture by which the left auricle joins the ventricle.
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.
Each auricle forms the terminal enlargement of the efferent vein of the ctenidium of its own side.
Heart has only a single auricle, neither heart nor pericardium traversed by rectum.
No ctenidium, but a pulmonary cavity; heart with a single auricle, not traversed by the rectum.