PLATE IV. 



Fig. i — 8. Placospongia melobesioides . 



Fig. i (1033). a — o Parenchymal tylostyles, s — 5 cortical tylostyles, 1 — >. sterrospirae ; X 96. 



Fig. 2 (1033). a— [i Portions of parenchymal tylostyles; y — r) portions of cortical tylostyles; 

 X 360. 



Fig. 3 (1033). Spherules of different size ; X 1000. 



Fig. 4 (1033). Idem; X 1400. 



Fig. 5 (1033). a — £ Different stages of development of sterrospira; 1000. 



Fig. 6 (1849 a). v. Tylostyle from the parenchyma ; fi tylostyle from the cortex; 96. y — o 

 Extremities of tylostyle a\ s — 'C cortical tylostyles; X 360. t\ Modified sphe- 

 rules; < 1400. 



Fig. 7 (1849 b). a Early stage of sterrospira; [3 spheraster; 1000. 



Fig. 8 (660 a). a — [i Parenchymal tylostyles; y cortical tylostyle; X 96. r) — c Portions of iel. ; 

 X 360. £ — ■/) Sterrospirae; 5 two spherasters; x 96. 1 Young stage of sterro- 

 spira; * spheraster; x 1000. 



Fig. 9 — 15. Placospongia cariuata. 



Fig. 9 (163a). a — 'C, Parenchymal tylostyles; t\ — 3 cortical tylostyles; X 96. 1 — z Portions of 

 parenchymal tylostyles ; / — - different stages of development of sterrospira ; 

 X 360. u — 6 Microspirae ; u — aa two stages of development of sterrospira ; 

 [5(3 parenchymal spinispira; X 720. yy ld. ■ 1000. dr) — Zfe ld. X 720. 



a — r) Spinispirae; X 500. s ld. X 1000 ; 'C, — r, probably early stages of sterro- 

 spira; X 1400. 5 — v Microspirae; X 1000. 



a Spheraster; |J — y spinispirae; r) — x microspirae; X 500. 



v Microspira ; X 1000. p Spinispira; • 500. y Idem; X 1400. 



a — y Cortical tylostyles; r) — ^ parenchymal tylostyles; x 96. jj — 1 Spinispirae; 

 X 500. 



Stage of development of sterrospira; x 1000. 



a — <? Four stages of development of sterrospira; a ■ 1000 ; p — d x 360. 



