PLATE XIII. 



Fig. 1. — Sp/ifierofi/lus antarcticus. Section of young specimen (X 3). 



Fig. 2. — Section of same (x 20). 



Fig. 3.— Dermul pores ( x 100). 



Fig. 4.^Inner surface of cortex showing terminations of pore canals ( x 1 00). 



Fig. 5. — Horizontal section of papilla (x 15). 



Fig. (;.— Vertical longitudinal section of papilla (x 15). 



Fig. 7. — Diplodal flagellated chambers ( x 400). 



Fig. 8. — Sphcterotylus capitatus (Vosmaer) choanosonial tjle (x 100) ; 8a, head of the same (x 100). 



Figs. 9, lo. — Smaller tyle and sub-tyle from spread out ends of radiiiting fibres of skeleton (x IGO). 



Fig. 11. — Cortical tyle, also found in choanosome between the main fibres (x 100). 



Fig. 12.— Smallest kind of cortical tyle (x 100) ; 12a, the same (x 100). 



Fig. l:;.— Exotyle (x 100) ; l:ia, clavate head of same (425). 



