Plate 11. 



Fig. 1. Hexactinella labyrinthica. Lateral surface of skeletal plate. Vertical beams in 



figure are radial to sponge surface; macerated 

 preparation; x 70. 



2. " " Small scopula ; x 600. 



3. " " Discohexaster ; x 600. 



" 4. " " Dermal oxydiact; middle region and the two ends; 



X 600. 



" 5. " " Dermal pentact («), and aberrant proximal rays of 



two other peutacts (6, c) ; x 170. 



" G. " " Dermal membrane, showing pores and supporting 



pentact rays ; x 100. 



" 7. " " Section, vertical to surface. Just beneath dermal 



membrane are a large, and two small, afferent 

 canals. Shaded tissue densely filled with flag- 

 ellated chambers and small canals ; x 70. 



