PLATE XII. 



FII,. 1. A. Sphaerotylus antarcticus Kirkp. Nat. size ; p. 16. B. Polymastia invagiiutta Kirkp. ; 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 Sphaerotylns capitatw 

 Vosmaer, nat. size ; p. 18 ; the smaller is S. antarcticus. 



FIGS. 2, o. fyhaernfylm antarcticus, young specimens. Nat. size. 



FIG. 4. Portion of another young specimen ( x 25). 



Fiu. 5. Sphaerotylus a/itttn-t/i-t/x. 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) ; Sa head of same (x 425). 



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



FIG. 13. Slender curved choanosornal tyle (x 100). 



FIG. 14. Beaded tyle from radial fibres (x 425). 



FIG. 15. 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). 



