PLATE 12 



EXPLANATION OF FIGURES 



Figure 25 is an injection of the early heart plexus, demonstrating the main 

 jugular and pericardial connections. Figures 26 and 27 (R. palustris, 10 mm.) 

 are two views of a specimen in the stage described for figures 23 and 24, in which 

 are added features not shown in that specimen. Thus the ventral lymphatic, and 

 lateral and dorsal plexuses are given in full, with the dorsal reception duct and 

 the pronephric plexus. In the dorsal view (fig. 27) the beginning of the anterior 

 accessory dorsal lymph system in the head and the special relations of the dorsal 

 reception duct are given. In the inset (fig. 27b) are given details of heart rela- 

 tions, together with the origin of the pericardial lymphatic. 



Ill 



