DlCTY OSPONGID jE. 



385 



gloriosa, and other species, we have to conclude that it belongs to a large 

 hexact or pentact whose precise position in the skeleton still remains in doubt. 



Smooth, elongate siliquate diacts (figure 41) of small size are occasionally 

 found among the parenchymalia. 



After careful search this species has afforded no evidence of umbels such 

 as occur in P. Colletti and Cleodictya gloriosa. Nevertheless it seems prob- 

 able that they exist, though they may be of great rarity. 



Dimensions. The size of this species, in comparison with its closest ally, 

 P. Colletti, is always small. An individual of rather large dimensions has a 

 length of 70 mm., an apertural diameter of 80 mm., and a basal diameter of 

 30 mm. Fragments of somewhat larger examples have been observed. An 

 average specimen which seems to be complete, is 45 mm. in length, has a basal 

 width of 50 mm., contracting above this to a width of 14 mm. and expanding 

 again to an apertural diameter of 60 mm. 



Locality. Physospongia I><nrs,>ni is known only from the calcareous shales 

 of the Keokuk group at Crawfordsville and Indian Creek, Indiana. 



Physospongia Colletti, Hall. 



Plate i.xiii, Figs. 1-7. 



1881. Plujsosponcjia Colletti, Hall. Thirty-fifth Ann. Rept. N. Y. State 

 Mus. Nat. Hist,, p. 180, pi. xx, fig. 7. 



Sponge large, rapidly, and sometimes ansymmetrically expanding from a 

 inoad base to a wide aperture. 



Surface highly nodose, similar in structure and aspect to that of P. 

 Dawsoni, but with nodes of much greater size, and with more frequent irreg- 

 ularities in their arrangement. 



Peticulu/n. The primary and secondary vertical bundles are of very 

 unequal size. The former are broad and compact over the lower portion of 

 the sponge but become diffuse above, spreading into a fan-like brush near the 

 aperture and obscuring therein' some of the main quadrules. Over the median 

 and lower portion of the cup the quadrnles are nearly square but toward the 

 aperture both nodes and concavities become transverse, the horizontal diame- 

 ter increasing and the vertical diameter lessening, until each division becomes 

 very narrow. Thereupon ensues a multiplication in the number of vertical 

 rows of nodes and depressions, the two rows of any one of the main vertical 

 divisions of the surface increasing to four, and the area occupied by each large 

 node or depression over the body of the cup bears two small nodes and cor- 

 responding depressions. This duplication of the vertical rows of quadrules is 

 25 



