360 



Report of the State Geologist. 



The general surface is smooth, gracefully expanding to the bulbous swell- 

 ings, thence sloping with gentle concavity to the oscula. 



The reticulum is fine-meshed. Since only the outer portion is exposed, 

 the vertical spicular bundles are not visible, but a fragment of a very large rod 

 is seen in the accompanying figure. At the angles of the prevailing quad- 



FlODRE 23. Spicules of Uastodictya otculata, X400. (J. M. C.) 



rules, which measure about 1.5 mm. on a side, there are very strong pentactins 

 or hexactins with modified outer arm, and lateral arms extending for nearly 

 the entire length of the quadrule. An extremital fragment of one of these 

 is represented in the above figure which also shows a many-toothed umbel 

 and a siliquiform diactin. 



Locality. In the calcareous shales at Crawfordsville, Indiana. 



PRISMODICTYA, gen. nov. 

 (For description see page 819, part 1.) 



Prisjiodictya polyhedka, sp. nov. 



Plate lv, Figs. 1, 2. 



Sponge large, subcylindrical, obscurely polyhedral, slightly expanding 

 toward the top. Surface regular and uniformly free of asperities, nodes or 

 protuberances except such as are produced by the slight outward extension 

 of the principal spicular bundles. In the best preserved of the compressed 

 specimens each .side bears five broad vertical faces, and at the edges are traces 

 of two more, twelve in all. These prism-faces make low angles with one 

 another, becoming obsolete at the even and regular margin of the osculum. 



