PLATE XII. 



Pig. 1. — A. Sphaerotylus antarcticus Kirkp. Nat. size ; p. 16. B. Polymastia invaginata Eirkp. ; p. 15. 

 (Note. The surface pile is, in the natural condition, more upright than in this specimen, where it 

 has been crushed down.) C. The larger of the two small specimens above C is Sphaerotylus capitatus 

 Vosmaer, nat. size ; p. 18 ; the smaller is S. anta/rdicus. 



Figs. 2, 3. — Sphaerotylus antarcticus, young specimens. Nat. size. 



Fig. 4. — Portion of another young specimen (x 25). 



Fig. 5. — Sphaerotylus antarcticus. A spheroidal specimen. Nat. size. 



Fig. 6. — Style from radiating main fibre (x 100). 



Fig. 7. — Style from inner cortical tangential layer ( x 100). 



Fig. 8.— Spherostyle (x 100) ; 8a head of same (x 425). 



Figs. 9-12. — Heads of various spherostyles (x 425). 



Fig. 13.— Slender curved choanosomal tyle ( x 100). 



Fig. 14. — Beaded tyle from radial fibres (x 425). 



Fig. 16.— Curved cortical tyles of outermost layer of cortex (x 100) ; 15a, the same (x 160). 



Fig. 16. — Straight tangential tyle of lower cortical layer (x 100) ; 16a, the same (x 425). 



