AOT) PHYSIOLOGY OP THE SPONGIADH:. 
1091 
Tabular View of Systematic Arrangement. 
Class. 
Order. 
Suborder. 
Genera. 
POEIFERA. 
I. CALCAEEA. 
II. SILICEA. 
1. Spiculo-radiate skeletons . 
Grantia, Fleming. 
Leucosolenia, Bowertanlc. 
Leuconia, Grant. 
Leucogypsia, BowerhanTc. 
Spiculo-menibranous skeletons 
Spiculo-reticulate skeletons 
Spiculo-fibrous skeletons 
Compound reticulate skeletons 
Solid siliceo-fibrous skeletons 
Canaliculated siliceo-fibrous skeletons 
III. KEEATOSA. 
1. Solid non-spiculate kerato-fibrous skeletons ... 
2. Solid semispiculate kerato-fibrous skeletons ... 
•3. Solid entirely spiculate kerato-fibrous skeletons 
4. Simple fistulo-fibrous skeletons 
5. Compound fistulo-fibrous skeletons 
6. Eegular semi-areno-fibrous skeletons 
7. Irregular and entirely areno-fibrous skeletons 
Geodia, Lamarck. 
Pachymatisma, BowerlanJc. 
Ecionemia, Bowerhank. 
Alcyoncellum, Quay et Gaimard. 
Polymastia, Boicerhank. 
Halyphysema, Bowerhank. 
Ciocalypta, Bowerhank. 
Tethea, Lamarck. 
Halicnemia, Bowerhank. 
Dictyocylindrus, Bowerhank. 
Phakellia, Bowerhank. 
Microciona, Bowerhank. 
Hymerapbia, Bowerhank. 
Hymedesmia, Bowerhank. 
Hymeniacidon, Bowerhank. 
Halichondria, Fleming. 
Hyalonema, Gray. 
Isodictya, Bowerhank. 
Spongilla, Linnceus. 
Desmacidon, Bowerhank. 
Eaphyrus, Boiuerhank. 
Diplodemia, Bowerhank. 
Dactylocalyx, Stutchhury. 
Parrea, Bowerhank. 
Spongia, Linnaeus. 
Spongionella, Boiverhank. 
Halispongia, Blainville. 
Clialina, Grant. 
Verongia, Bowerhank. 
Auliskia, Bowerhank. 
Stematumenia, &c., Bowerhank. 
Dysidea, Johnston. 
Order I. CALCAEEA. 
The number of species of calcareous sponges that are known is comparatively so 
small, and the four genera into which I have divided them are naturally so well charac- 
terized, as to render the establishment of suborders unnecessary. Hereafter, when we 
are acquainted with a greater number of species, and other varieties of organization 
become known, the genera now established may become the types of suborders, for 
which office their distinctly different modes of construction render them eminently 
efficient. 
Although the calcareous structure of the species of this order appears to entitle it to 
precedence in the arrangement of the Spongiadae, it does not maintain in the structure 
of its skeleton throughout the whole of the genera the same high type of formation 
