208 EXPLANATION OF THE FIGURES. 



//, the mantle, slit open. 



g, the edge of the mantle, over the neck. 



h, the branchia. 



I, the branchial vein. 



J, the heart. 



k, the branchial artery. 



/, the extremity of the intestine. 



»i, the intestine. 



n, the stomach and liver, in the convoluted part of the 



body. 

 0, the oviduct. 



p, the cerebral ganglion and nerves. 

 q, the salivary glands. 

 r, the fringed membrane which borders the left side of 



the opening of the respiratory cavity beneath. 

 Fig. 9. Mactra Stdltorum. 

 a a, the left valve of the shell, the right having been 



removed. 

 h b, the left lobe of the mantle, lining the valve. - 

 c, the anterior adductor muscle. 

 </, the posterior adductor muscle. 



e, the mouth, and part of the oesophagus. 



f, the two oral appendages, or tentacula. 



g, the stomach, 



h, the elongated appendage of the stomach. 



i, the intestine, convoluted in and around the liver. 



j, the liver. 



/i, the large, bent, tapering, compressed foot. 



/, the rectum passing through the heart. 



m, the end of the rectum. 



n, the anus or termination of the rectum. 



o, the upper siphon, for the passage of excrement. 



p, the lower siphon, for respiration. 



q, the branchiae of the left side. 



r, the anterior ganglion. 



s, the posterior ganglion. 



t, interganglionary nerve. 



