PLATE IX. 



PAGE 



Fig. 1. Rhizochalina 2yii'tridosa, oxen fvom the inteviov oi theaijouge ; x 325, . 34 



Fig. 2. Rhizochalina pedunculata, strongyla from tlie dermal layer ; a, d, adult ; 



b, c, probably young forms, showing central inflation ; x 325, . 35 



Fig. 3. Oceanapia rohusta ; a, 5, c, uxca ; ri, sigmata ; x 325, . . .37 



Fig. 4. Rhizochalina Jistulosa, oxea ; a, h, adult; c, young; x 325, . . 32 



Fig. 5. Siderodcnaa navicelligerum ; a, h, tylota ; c, trichodragma ; d, larger 



sigmata ; e, smaller sigmata ; /j minute isuchela? ; x 175, . 115 



Fig. G. Rhizochalina pedunculata, oxea from the interior of the sponge ; x 325, 36 



Fig. 7. Rhizochalina piutridosa, portion of the end of a fistula, showing the arrange- 

 ment of the spicules ; a, fibres of the " bast " layer ; h, tufts of spicules 

 echinating them, ....... 34 



Fig. 8. Sideroderma navicelligerum, minute isochclse, side and front views ; 



X 1400, ........ 116 



Fig. 9. Sideroderma navicelligerum, portion of vertical section of rind, showing 

 the alternating layers of spicules ; a, cut ends of spicules ; h, longi- 

 tudinally placed spicules ; c, outermost layer without spicules, . 115 



