lOO BLOOMER : ON THE BRITISH SPECIES OF THE GENUS SOLEN. 



which have their walls pierced with small holes. In the mantle these 

 are large trunks which form lateral openings. This fact may be 

 explained by the rapid displacement which the blood has to submit 

 to at times. Besides this, in consequence of the respiratory function 

 of the mantle, the blood must spread over as large a surface as 

 possible. 



S. siliqua, L. 



'J'he arterial system of /S. -fi/iqua is similar to that of *S. cnt>is, and 

 only differs from it in a few minor details which it is unnecessary to 

 enumerate. 



S. manji//afi(>i Pult and Don. 



The arterial system of *S'. rnayijinatu^ is somewhat different owing 

 to the anterior portion of the animal being shorter than in the species 

 ends and siliqua. The anterior aorta is dorsal to the anterior end of 

 the right lobe of the liver, before curving and proceeding in a ventral 

 direction. 



From the pedal artery arises a large branch which also vascularises 

 the viscera and particularly the caecum of the crystalline style. The 

 pedal artery being more superficial forms fewer branches, but at the 

 point of the terminal curve of the intestine it gives off a large lateral 

 branch which passes between the muscular bundles of the distal end 

 of the foot. 



EXPLANATION OF PLATE VIIL 



Fig. 17. Semi-diagrammatic view of Solcit oisis from the left side, showing the 

 circulatory system. 



Reference Letters. 



Anus. 



Auricle. 



Anterior adductor muscle. 



Anterior aorta. 



Artery of the Anterior 



adductor muscle. 

 Anterior adductor sinus. 

 Afferent branchial vessel. 

 Anterior pedal sinus. 

 Msceral artery. 

 P.ulbus arteriosus. 

 Caecum of crystalline style. 

 Efferent branchial vessel. 

 Fourth aperture. 

 Intestine. 

 Kidney. 

 Left lobe of liver. 



