PLATE 10 



EXPLANATION OF FIGURES 



Figure 19 demonstrates, in :i later stage (R. palustria), the continued plexiform 

 character of the walls of the temporal sinus, with a lateral view of the central sub- 

 maxillary sinus and its anterior circum-oral and inandihular processes. The peri- 

 cardial sinus is attached posteriorly. This figure is readily compared to figure 22, 

 which is a ventral view of an older larva of 12 mm. with intestinal spiral. The 

 later condition of these sinuses, shown to the right in the reproduction of Hover's 

 figure 3 ('05), of a 26-mm. larva (R. temp.), is explained by the fusion in front 

 of the earlier inandihular circum-oral and temporal sinuses and of tin- central. 

 temporal, and pericardial sinuses at the back. 



107 



