EXPLANATION OF PLATE XXI. 

 Lop/iophysema inflatv/m. F. E. Sch. 



Fig. 1. Bchematic representation of a longitudinal section to show the 

 relation between the in- and ex-current canals. One-third of the nat. size. 



Fio-. 2. Arrangement of the spicules in a transverse section of a plate 

 dividing an in- from an ex-current cavity. The dermal surface is to the left, the 

 gastral to the right. X 50 (combined figure). 



Fio-. 3. Arrangement of the spicules in a transverse section of the 

 marginal crest. The dermal surface is below, the gastral above, x 50 (combined 

 figure). 



Figs. 4 and 5. Parenchymal, intermediary oxyhexactines. x 300. 



Fig, 6. Canalar pentactine pinule. x 300. 



Fig. 7. Dermal pentactine pinule. x 300. 



Fig. 8. Oxydiactine marginal. x 300. 



Fig. 9. Parenchymal diactine from the neighbourhood of the central cone. 

 X 100. 



Fig. 10. Macramphidisc. x 300. 



Fig. 11. Stauractine acanthophor. x 300. 



