PHYLUM MOLLUSCA 



247 



through the posterior aorta (p.ao). Part of the blood passes into 

 the mantle, where it is oxygenated, and then returns directly 

 to the heart. The rest of the blood circulates through numerous 

 spaces in the body and is finally collected by a vessel called 



.sph. 



in.sph 



gori 



hd wt 



Fig. 175. — Internal anatomy of Anodonta cygnea, dissection from the left 

 side, a, the anus ; a. ad, anterior adductor ; a.ao, anterior aorta ; a. v ap, 

 auriculo-ventricular aperture ; bl, urinary bladder ; c.pl.gn, cerebro-pleural 

 ganglion; d.d, duct of digestive gland; d.gl, digestive gland; d.p.a, dorsal 

 pallial aperture ; ex. sph, exhalent siphon ; ft, foot ; g.ap, genital aperture; 

 gon, gonad; gul, gullet; i.l.j, interlamellar junction; in.sph, inhalent siphon; 

 inl, intestine ; hd, kidney ; m, mantle ; mth, mouth ; p.ao. posterior aorta; 

 p.ad, posterior adductor; pc, pericardium; pd.gn, pedal ganglion; r.ap, renal 

 aperture; r.au, right auricle; ret, rectum; r.p.a, reno-pericardial aperture; 

 st, stomach; ty, typhlosole; v, ventricle; v.gn, visceral ganglion; w.t, water- 

 tubes. (From Parker and Haswell.) 



the vena cava, which lies just beneath the pericardium. From 

 here the blood passes into the kidneys, then into the gills, and 

 finally through the auricles and into the ventricle. Nutriment 

 and oxygen are carried by the blood to all parts of the body, 

 and carbon dioxide and other waste products of metabolism are 

 transported to the gills and kidneys. 



