11 



Fig. 80. Structure of rectal gills. 1. From main-fold in fig. 79 A. 2. From main- 

 fold of Hemigomphu* heteroclitus Selys (papillate simplex). 3. A single papilla 

 of same, apical third. 4. From a gill in fig. 79 B. 5. Two foliae from posterior 

 portion of gill-basket shewn in fig. 79 c. 6. Two papillo -foliae from fig. 79 D. 

 7. A single papilla of same, apical half. 8. Three lamellae from fig. 79 E. 

 9. Three lamellae of Austrocordulia refracta Tillyard. 10. Supra-vortical 

 papilla of same. 11. Ten lamellae from fig. 79 F. (1, 2, 4, 8-11, x75; 

 6,6, x40; 3, x460; 7, x680; 10, x570.) Original, from photomicrographs. 



