RpKciKfl OK TiiE Keokuk (tkoup. 189 



Similar skeletal structure is also to be found in the genus Koemeri- 

 BPONGiA of the middle Devonian of Germany {R. Gerohtelnemiii, F. Roemer ; 

 see part 1, page 67). 



In Ameiican faunas species of Piiysospongia are known only from the 

 Keokuk group, all specimens having been derived from the calcareous shales 

 in the vicinity of Crawfordsville, Indiana, 



Physospongia Dawsoni, Whitfield (sp.). 



PtATE Lxii, Figs. 1-10. 



1881. Uphantcenia Daiosoni, Whitfield. American Journal of Science, 

 vol. xxii, 3d ser., p. 132. 



1881. TTphantoBnia Dawsoni, Whitfield. Bull. No. 1, Amer. Mus. Nat. Hist., 



p. 15, pi. iv, figs. 1, 2. 



1882. Physospongla Dawsoni, Hall. Notes on the Family Dictyospongidae ; 



Expl. pi. 19, figs. 4-6, 8 (not fig. 7). 

 1884. Physospongla Dawsoni, Hall. Thirty-fifth Ann. Kept. N. Y. State 

 Mus. Nat. Hist., p. 479, pi. 19 (20), figs. 4-6, 8. 



Sponge subcylindrical over the body and lower portion, expanding some- 

 what more rapidly toward the aperture. In the majority of specimens the 

 cup seems to taper quite rapidly toward the base, but the base itself was 

 evidently broadly obtuse, and in some instances slightly expanded. This por- 

 tion of the cup is seldom retained. Size comparatively small, rarely exceeding 

 a length of 75 ram. with a nearly equal width at the aperture when under 

 compression. As usually preserved the width of the cup at the upper end is 

 about one third greater than at the lower end ; occasionally the former is 

 twice that of the latter. 



Metioulum. The primary reticulation of the surface is very coarse and ia 

 produced by a double series of vertical spicular bundles intersecting a single 

 series of horizontal bands. Of the vertical bundles the principal series ia 

 broad and flat, its width being from three to five times that of the secondary 

 series. There is a notable increase in width from below upward in the prin. 

 cipal bundles, as occurs in P. Colletti. The principal and secondary vertical 

 bundles alternate in position and are equidistant, the latter equally dividing 

 the area set off by the former. The horizontal bands are narrow, caiTying 

 about the same number of spicular rods aa the secondary vertical bundles. 

 The intersection of these with the principal vertical bundles divides the sur- 

 face into equal quadrules, each of these being sub-divided into four equal 



