PLATE VI. 



PAGE 



Fig. 1. EDRIOSPONGIA BAS ALIS U, & E.. and ANTHASPIDELLA, sp 272 



1. Upper surface of specimen showing the osculiferous face of the Antltax- 



pideUa, and to the right portions of the Edrlospongia. Natural sine. 

 1 a. Lateral view of same, showing the rough base of the Xdriotfonoia, 



its irregular sides, and above, the close union it forms with the Anthnn- 



pidella. 

 1 b. Portion of a smaller specimen of E. basalts with the upper surface 



ground away and polished to show the arrangement of the canals. 



Natural size. 



1 c. Thin transverse section showing the spicular skeleton, x!8. 



Trenton limestone, Dixon, 111. Illinois State Musoum. 



Fig. 2. B ATOSPONGIA 8PICATA CIrich 246 



2. View of the lower side from which the dermal layer has bom withered 



away. Natural size. 



2 a. A bunch of spicules of same, freed from the matrix by mean* of m-id, 



x 18. 



2 b. The inner side of the basal or dermal layer, x 18. 



Lower Coal Measures, Seville, 111. Illinois State Museum. 



Fig. rSTBIOSPONGIA CABBONAEIA Ulrich 245 



3. A number of the needle-shaped and one four-rayed spicule, x i r >. 



3 a. A free four-rayed ?picule found associated with the single forms, x 25. 



Lower Coal Measures, Seville, III. Illinois State Museum. 



