828 
DE. J. S. BOWEEBAJS'K ON THE ANATOMY 
relative positions of the spicula in the skeleton: — «, a spiculnm from the 
same ovarium, detached, x 308 linear : page 811. 
Fig. 9. A perfect skeleton of an ovarium of Sjpongilla fluviatilis, prepared with nitric 
acid, X 183 linear : page 811. 
Fig. 10. A skeleton of an ovarium of Spongilla lacustris, prepared -with nitric acid, 
exhibiting the spicula in situ and the foramen, X 183 linear : page 811. 
Fig. 11. Two of the reticulated cases of the ovaria of Spongilla JBrowni% Boweeban:k, 
MS. : — 05, an empty case ; J, a case containing the skeleton of an ovarium, 
X 50 linear : page 813. 
Fig. 12. A reticulated case of an ovarium of Sjpongilla reticulata, Bowebbajvk, MS., 
X 175 linear: page 812. 
Fig. 13. Skeleton of an ovarium of Spongilla reticulata, Bowerbajstk, MS., without its 
case, prepared with nitric acid, X 175 linear : page 812. 
PLATE XXXIV. 
Fig. 1. A perfect ovarium of Dijplodemia vesiculata, Bowerbank, MS., and a portion of 
a second one, showing the interior and the thickness of its walls in its natm-al 
state, X 83 linear : page 813. 
Fig. 2. An ovarium of Geodia M'Andrewii, Boweebank, MS., in very nearly an adult 
state, showing the structure and position of the conical foramen for the 
discharge of the ova, natural condition, X 183 linear: page 815. 
Fig. 3. A small portion of the surface of a fully-developed ovarium of Geodia M‘An- 
drewii in its natural state, showing the distal ends of the spicula flat and 
angular, and firmly cemented together, X 308 linear : page 815. 
Fig. 4. A portion of a young ovarium of Geodia M^Andrewii, with the distal ends of its 
spicula acutely terminated, and unconnected, X 308 linear: page 815. 
Fig. 5. A portion of a section through nearly the centre of a mature ovarium of Geodia 
M'^Andrewii, showing the radiation of its spicula from near the centre to its 
circumference, X 308 linear : page 815. 
Fig. 6. Two ovaria of Geodia Andrevoii, (a) containing about the maximum of ova, 
(d) after a great part of the ova have been discharged, X 108 linear : 
page 814. 
Fig. 7. A mature ovarium of Pachymatisma Johnstonia, Bowerbank, exhibiting the 
cuneiform spicula of the foramen, X 308 linear : page 815. 
Fig. 8. A young ovarium of Pachymatisma Johnstonia in course of development, X 308 
linear : page 815. 
Fig. 9. A young ovarium of Pachymatisma Johnstonia in a very early stage of develop- 
ment, X 308 linear : page 815. 
Fig. 10. An ovarium from a sponge from Madeira closely allied to Pachymatisma., 
exceedingly depressed and much elongated, X 308 linear : page 815. 
