270 DltriYOSPONGID^. 



PLATE XXXVI, 

 HYDNOCERAS, Conrad. 



Page 95. 

 (See Plates II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XXXIII, XXXVII, XXXVIII, XXXIX, XLVI.) 



Hydnocekas vakiabile, sp. nov. 



Page 108. 

 (See Plate XXXVII.) 



Figure 1. The apical portion of a specimen with coarse, strong, subequal 

 meshes. There is no indication of nodes upon the surface of the 

 cast, except near the broken end, but the matrix shows the pres- 

 ence of nodal tufts in this region. 

 Lower Chemung. Deyo basin, Naples, New York. 



PEISMODICTYA, gen. nov. 



Page 79. 

 (See Plates XVII, XVIIT, XIX, XX, XXI, XXVII, XXXHI, XXXIV, XXXV, XIJ, XLII, LV.) 



PlUSMODICTYA AMICITI^, Sp. IIOV. 

 Page 87. 



Figures 2, 8. Two specimens which show the elongate and slender form of 

 the s])ecies, with the abrupt and gradually declining expansion of 

 the sponge above the base. 



Figure 4. This specimen, found in association with numerous individuals of 

 this species, shows a spiral twisting of the frond, resulting from 

 abnormal growth. 

 Chemung group. Frietidship, New York 



Pkismodictya cithaea, sp. nov. 



Page 90. 

 (See Plate XXXV.) 



Figure 5. A large and somewhat distorted specimen of this species in which 

 the nodes up{m the expanded portion are rendered conspicuous by 

 compression of the prism-faces. 

 Chemung group. Scio, New YorTc. 



