224 



PALAEONTOLOGY OF ILLINOIS. 



Fig. 1. Two columns of spicules of CZimacosponffia radiata Hinde, magnified 25 times. 

 Drawn from a gutta-percha cast taken from a natural mould. The specimen 

 is from the Niagara group of Perry county, Tenn. The finer details of struc- 

 ture are not preserved. 



Fig. 2. End view of several columns of same, showing their arrangement and the con- 

 necting bars. 



Fig. 3. Spicules of Astylospongia proemorsa Boemer, mag. 25 times, as shown in 

 gutta-percha casts. Niagara group, Perry county, Tenn. 



Fig. 4. Taken from another gutta-percha cast of CUmacotpongia radiata Hinde; x 25. 

 In this cast the structure of the columns is shown in a very satisfactory man- 

 ner. Position and locality same as for fig. 1. 



Fig. 5. End view of a single column of preceding; x 25. 



Fig. 6. Diagrammatic view of a spicule of Climacospongia and of the Anthaspidellidas 

 generally. 



