246 DicrYospoNGii)^. 



PLATE XXIV. 

 THYSANODICTYA, gen. nov. 



Page 125. 

 (See Plates XIX, XXIII, XXV, XXVI, XXVII, XXXVIII, XXXIX, XL, XLII, LIII.) 



TiiYSANODicTTA Edwin-Halli, iiom. nov. 



Page 126. 



Figures 1, 2. Opposite sides of a nearly entire cap of average size; showing 

 the broad, oblique aperture, the basal disk and the coarse primary 

 reticulation. 



Figure 3. A much more slender specimen, showing both the primary and 

 subordinate reticulation. 



Figure 4. A portion of the surface of another specimen, showing primary 

 and secondary reticulation. 



Figure 5. A small specimen exposing a part of the basal disk. 



Figure 6. The lower portion of a specimen, showing tlie basal disk. 



Figure 7. A view of the same specimen lying in its matrix and showing the 

 broad frill at the periphery of the basal disk. 



Figure 8. A flattened but essentially entire sponge in which only the strong 

 primary quadrules are shown. 



Figure 9. An incomplete specimen showing the finer reticulation. When pre- 

 served in this condition these specimens are hardly to be distinguished 

 from internal casts of Olathmspotigia abacus (see Plate 49, figure 8). 

 Chemung group. Wellsville, New Yorh. 



Thysanodiotya pcecilus, sp. nov. 



Page 127. 



Figure 10. A very elongate individual, having the prevailing form of the 

 primary (j^uadi-ules nearly scpiare; showing, also, some of the tufted 

 intersections of the erect surface lamellae. 



Figure 11. A broader individual, showing the complete outline of the body 

 of the sponge, its aperture and base and the strong erect vertical 

 lamellae and their intersections with similar horizontal lamellae. At 

 the base, on one side, a portion of the basal frill is retained. Both 

 this and the preceding specimen are preserved on the same slab in 

 association with other forms less complete but showing less extreme 

 outlines. 

 Chemung group. Scio, Allegany county, New Yorh. 



TiiYSANODicTYA Randalli, Hall (sp.). 



Page 129. 



Figure 12. A view of the original specimen which is a fragment of the 

 upper portion of a cup showing the character of the reticulation. 

 Chemung group. Warren, Pennsylvania. 



