Speciks of tiik Ciiemuno Group. 117 



Dimensions. The only known example has a length of 280 mm. from 

 the aperture, which appears to be entire, to the broken basal e.xtremity ; a 

 width of 70 ram at the aperture and 20 mm. at the lower end. 



This description is based upon a plaster cast of a specimen formerly in the 

 possession of the late Rev. A. H. Riley, of Montrose, Pennsylvania, but 

 the present ownership of which is unknown. 



Locality. In the upper beds of the Chemung group at Great Bend, Sus- 

 quehanna county, Pennsylvania. 



CERATODICTYA, gen. nov. 



Elongate, gently expanding cups, transversely annulated and without 

 predominating ridges or other surface ornamentation. 

 Type, Dictyophyton annulatum, Hall. 



Ceratodictya Carpenteriana,* sp. nov. 



Plate xlii, Fig. 1 ; Plate xliii, Fios. 1-3. 

 Sponoe extremely elongate, slender, very gradually and regularly ex- 

 panding. Sometimes the cup assumes a gentle crescentic curve which appears 

 to be not abnormal though one specimen of considerable length is straight 

 thi'oughout its extent. The surface is covered by strong, regular, continuous, 

 duplex annulations separated from each other by deep grooves, both grooves 

 and annulations having about the same width over the median portion of the 

 sponge. The annulations are rendered duplicate by a transverse groove 

 on each, which under compression and especially on the incipient portions 

 of the skeleton, may sometimes approximate in breadth the interannular grooves. 

 Each annulation is thus divided into two well-defined ridges rounded at their 

 summits and with their deeper slope toward the interannular grooves. Some 

 variation is apparent in the form of these annulations during the process of 

 growth. Near the basal point the summit grooves are rel.atively nuich 

 broader than at any later growth-period, and although all observed specimens 

 of the species are noteworthy for the stability and uniformity of the annula- 

 tions, yet the example figured on Plate xliii (fig. 2), shows that the second 

 annulation which is, in fact, the upper member of the divided first annulation, 

 is itself faintly duplicate. As growth continues beyond maturity the inter- 

 annular grooves become diminished in width, and apertural fragments of full 

 grown and old specimens show that both grooves and annidations are much 



* Thus named as a token of respect and esteem for Mrs. Fannib Hall Carpenter, daughter of E. B. 

 Hall, Esq., of Wellsville, N. Y. 



