GENERAL ANATOMY OF A LAMELLIBRANCH. 



283 



(i.) The opening from the pericardium into the glandu- 

 lar portion will be found at the anterior end of the former, 

 just below the point where the intestine enters it. Pass a 

 bristle through it, into the non-glandular portion. 



(ii.) The non-glandular portion lies above and outside 

 of the glandular portion. Open it and find, at its ante- 

 rior end, the external opening into the cloacal chamber. 

 Notice, at its posterior end, its communication with the 

 dark-colored, thick-walled, glandular portion. 



Li 



FIG. 145. 



FIG. 145. Diagram of Bojanus organ of Unio pictorum. (From 

 Bronn, Klassen und Ordnungen, Malacozoa. Tab. xxxii. Fig. 11.) 



a. Glandular portion of organ of Bojanus. a'. Non-glandular portion. 

 L Opening from pericardium into glandular portion. I. External open- 

 ing of non-glandular portion, m. Reproductive orifice, n. Ventricle. 

 n 1 . Pericardium. L Rectum. 



(iii.) Cut through the floor of the non-glandular portion, 

 and lay open the glandular portion. Notice the bristle 

 which has been passed into it from the pericardium. 

 Notice that the glandular portion runs back much further 

 than the non-glandular portion, and becomes expanded at 

 its posterior end to form a large pouch, which rests against 

 the posterior adductor muscle. 



3. The blood from the various parts of the body finds 

 its way to the venous sinus, some of it passing through 



