GENERAL ANATOMY OF A LAMELLTBRAXCH. 



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. 



Fig. 145. 

 Fig. 145. — Diagram of Bojanus organ of Unio pictorum. (From 

 Jronn, Klassen und Ordnimgen, Malacozoa. Tab. xxxii. Fig. 11.) 

 a. Glandular portion of organ of Bojanus. o '. Xon-glandular portion. 

 N. Opening from pericardinm into glandular portion. I. External open- 

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

 »i Pericardium, t. Rectiuu. 



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



[and lay open the glandular portion. Xotice the bristle 



|which has been passed into it from the pericardium. 



i^otice that the glandular portion runs back much further 



jbhan the non-glandular portion, and becomes expanded at 



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



the posterior adductor muscle. * 



3. The blood fix)m the various parts of the body finds 



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



