Paleontology of the Cincinnati Group. 53 



2. Leptopotcrion — 01)Conical ; surface anmilated or re- 

 ticulated. 



3. Microspongia — Compact; radiate in structure and with- 

 out large openings. 



4. Hindia — Splucroidal ; a central space with spicuhe ; 

 canals opening at the surface. • 



5. Cylindrocoelia — Cylindrical; pointed or truncate, hollow. 



6. Rhonibodictyon — Globular or discoid ; rods crossing each 

 other nearly at right angles, thus forming rhombic spaces. 



tt Surface with plates. 



7. Pasceolu.s — Plates polygonal and without special arrange- 

 ment. 



8. Receptaculites — Plates arranged in intersecting lines ; 

 imbricated or c}-lindrical. 



b. Body cavity hollow, sponge cup-shaped or funnel-form. 



9. Cyathophycus — Hollow, cylindrical, with a reticulated 

 structure. 



10. Chirospongia — Hollow, general form hand-like ; .struc- 

 ture vesicular. 



1 1. Bracliiospongia— Body circular, cup-shaped, with spread- 

 ing arms. 



c. Amorphous. 



12. Pattersonia — -Irregular in form, generally compressed, 

 and appearing as if a number were united- 



13. Dystactospongia — Canals on exterior radiating from a 

 common center. 



d. Branching. 



14 Heterospongia — Outer surface showing oscula and 

 mouths of canals. 



Genus i. — AsTvi.ospoNCii.v, Roemer, i860. 



Free, globular or spherical, and nearly circular. The inner 

 tissue made up of very regular stellate bodies (spicukc) 

 united by their rays. Large canals radiate from the center to 

 the circumference. These cross or are intersected b}' con- 

 centric canals. (Die Silur. fauna des West. Tenn., 1860, 

 pp. 7, 8.) 



