258 DlClYOSPONGlD^K. 



PLATE XXX. 

 ACTINODICTYA, Hall. 



Page 142. 

 (See Plato XXXI.) 



ACTINODICTYA PLACENTA, Hall. 



Page 143. 



(See Plate XXXI.) 



Figure 1. An irregiilai'ly oval frond showing great differences in the size of 

 the spicular bands. In this specimen these bands show an unusually 

 regular reticulation although the various series may intersect at 

 different angles. The drawing has Ijeen made with accuracy but 

 the apparent abundance of cruciform spicules is wholly due to 

 elevation of reticulating spicular bands at and near their intersec- 

 tions ; as these bands gradually die out, the more strongly projecting 

 portions produce the effect observed. 



Figure 2. Two essentially entire fronds, one j)artially overlapping the other 

 and somewhat broken near one extremity. This specimen Avith that 

 represented in figure 1 and that in figure 1 on Plate xxxi show the 

 form of this fossil at the locality where it has been found in the 

 greatest perfection and without evidence of much distortion. Such 

 specimens indicate that the bodies were broad, convex expansions, 

 evidently not of highly irregular growth but with a definite marginal 

 outline and uboval form. 



Chemung group. Orie-lialf mile from Brown hill, near Coliocton, 

 Meio York. 



Figure 3. A fragment of a specimen the surface of which bears irregularly 

 scattered spots representing subcircular perforations of the spicular 

 net- work. These may be to some extent due to accident. 

 Chemung group. Near Howard, New Yorh. 



