SpKcrKs OK TiiE Chkmuno Ghoth'. 125 



Locality. This sponge was obtained many years ago at Ithaca, N. Y., by 

 Prof. F. W. SiMONDS. Its precise position in the strata thei-e, whether from 

 the beds of the Portage or from those of the overlying Chemung rocks of the 

 vicinity is not known, 



ClATHROSPONGIA ( ? ) DESMIA, Sp. HOV, 

 Plate xxv, Fig. 3. 



A fragment of the surface of a flattened cup indicates, in the absence of 

 decisive generic characters, a species distinct from any of the forms elsewhere 

 described. The primary and secondary spicular bands are so nearly of the 

 same size that the surface appears to be divided into vertical rectangular 

 parallelograms which measure on the average, 3 mm. on the base and 6 ram. 

 in height ; that is, the horizontal bands over the entire extent of the exposed 

 surface are about twice as far apart as the vertical bands, and all leave im- 

 pressions of about the same strength upon the external cast. The predominant 

 rectangles are divided into squares, by faint transverse bands. All of the 

 principal spicular bands form erect lamellae without producing no<les at their 

 intersections. The form of the quadrule in this species is somewhat similar to 

 that prevailing in Dictyospongia sceptrum, but we are without evidence of the 

 existence of spicular lamellae in that species and genus. In Thymrwdictya 

 rvdis and T. Maiidalli the quadrules are larger and more nearly square. The 

 length of the fragment is 90 mm. and its greatest width, 40 mm. 



Locality. In the upper beds of the Chemung group near Alfred and at 

 Scio, ADegany county, N. Y. 



THYSANODICTYA, gen. nov. 



Subcylindrical or tapering Dictyosponges with prominent, projecting, 

 rectangularly reticulating spicular bands or lamellae forming series of fenes- 

 trated quadrules upon the surface, as in Clatiirospongia. Base ending 

 abruptly in a transverse disk or broad and shallow reticulated obcone 

 or basin, which may be encircled by an expanded bjisal fiill, as in 

 Phragmodictya. 



Type, Dictyophyton HalU, Hall. 



Species of this genus combine some of the characters of the two genera 

 last mentioned, and while the form of the sponge is similar to that of 

 Phragmodictya, it lacks both the irregular surface ridges of that genus 

 and also the regularly radiated reticulum of the diaphragm or basal 



