116 DiCTYOSl'ONGID.E. 



LocaliUj. From the upper beds of the Chemung group ; in the Prismo- 

 dictya prismatica colony, at Concord station, Erie county, Pennsylvania. 



Helicodictya (?) Scio, sp. nov. 



Plate xxvii, Fig. 1. 



Sponge moderately large and apparently regularly expanding. Surface 

 crossed by subequidistant spiral ridges from 17 to 20 mm. apart, revolving 

 from left upward and over to right. These are parallel to one series of 

 spicular bands, the principal reticulating series making therewith quadrules 

 measuring about 10 mm. on a side. The length of the original fragment is 

 about 70 mm. ; its width at the lower extremity 33 mm. and at the upper 

 extremity 55 mm. Its surface bears four spiral ridges. 



The reason for placing this form among the spiral sponges is simply the 

 aspect of the best preserved specimen. While the specific form may be 

 distinct, the evidence afforded by a second example indicates that the generic 

 reference here provisionally employed may be of doubtful value. 



LocaUtij. In the upper beds of the Chemung group at Scio, Allegany 

 county, N. Y. (Collection of E. B. Hall.) 



RHABDOSISPONGIA, gen. nov. 

 Elongate, broadly and strongly aunulated sponges, fluted by vertical 

 ridges. 



Type, Dlctyophyton AmaltJiea, Hall. 



Rhabdosispongia Amaltiiea, Hall (sp.). 



Plate xvi, Fig. 1. 



1890. Dietyophyton Amalthea, Hall. Ninth Kept. N. Y. State Greologist, 

 p. 58 ; Forty-third Ann. Kept. N. Y. State Museum, p. 260. 



Sponge slender, expanding veiy gradually, gently curved near the base ; 

 transverse section probably circular. In the original specimen the base is 

 wanting, but the remaindei- of the surface bears five broad and deep trans- 

 verse constrictions which increase in width toward the aperture. These give 

 to the cup the appearance of being strongly annulated, the annulaticms increas- 

 ing in breadth with the constiictions. The area about and below the aperture 

 is without constriction at the usual interval. The surface is ornamented by a 

 series of distant, longitudinal, narrow spicular ridges, diverging toward the 

 aperture with the expansion of the cup. Six or seven of these are visible 

 upon the exposed surface but no other trace of the reticulum is apparent. 

 The interspaces between these narrow ridges are flat and broad. 



