422 



Repokt of the State Geologist. 



PLATE LXIII. 



PHYSOSPONGIA, Hall. 



Page 379. 

 (See Plates LVI, LXI and LXII.) 



PlIYSOSPONGIA CoLLETTI, Hall. 

 Page 385. 



Figure 1. A nearly entire specimen of rather small size showing the usual 

 aspect of the species. The nodes have undoubtedly been somewhat 

 flattened, and the secondary vertical spicular bundles are represented 

 as rather too broad. 



Figure 2. An enlargement of a portion of the surface in the same specimen, 

 showing two nodes and their corresponding concavities, each pair 

 being separated by a major vertical spicular band. The surface of 

 the quadrules shows indications of a finer reticulation. 



Figure 3. A fragment of a large, somewhat irregular example, showing the 

 obsolescence of the nodes near the aperture. 



Figure 4. An enlargement of the surface in the smooth apertural region of 

 the foregoing specimen, showing the diminution in the size of the 

 spicular bundles. x2. 



Figure 5. The apertural major portion of a sponge ; showing the diffusion of 

 the vertical spicular bands of the first order, and the multiplication 

 of the quadrules by increase in the number of both horizontal and 

 vertical bundles. At the aperture all nodes and depressions have 

 become obsolete. 



Figure 6. A portion of the same specimen redrawn to show more distinctly 

 the multiplication of the nodes by horizontal and vertical division. 

 Natural size. 



Figure 7. A portion of a very large specimen, natural size, hi which the fine 

 reticulation of the quadrules is distinctly retained. 

 Keokuk group. Crawfordsville, India mi. 



