PLATE XVIII. 



PAGE 



Malacosaccus vastus, ¥. 'Ei. B., . . .91 



Fie. 1. Part of the lateral wall, preserved in alcohol, inside view ; natural size. 



Fig. 2. Section at right angles through the entire wall (combination figure) ; 

 X 20. 



Fie. 3. Small discohexaster from the trabecular framework ; x 450. 



Fig. 4. Part of a floricome from the outer (dermal) surface ; x 450. 



Fig. 5. Part of a small discohexaster (fig. 3) ; x 1000. 



Fig. 6. Part of a iioricome from the inner (gastral) surface ; x 1000. 



Fig. 7. Terminal ray of a floricome from the inner (gastral) surface ; x 1000. 



Fig. 8. Part of a hy^Dodermal hexact ; x 100. 



Fig. 9. Floricome from the inner (gastral) surface ; x 300. 



Fig. 10. Oxyhexaster with very slender long terminal rays ; x 300. 



y 



