SpKcrKs OF TirK CiiEMiJNO Guotrp. 127 



depressed basal diaphragm. The basal frill (periloph, Ilauff) is broad and 

 where best retained appears to be gently undulated, but tliis expansion is not 

 so preserved as to show clearly the character of the reticulation. The l)aMa1 

 diaphragm Is slightly convex or even concave, and bears a low but coarse 

 rectangular reticulation. 



Dimensions. A well developed individual of rather large size, measures 

 60 mm. from aperture to base. The aperture is 48 mm. and the base 26 mm. 

 in diameter; the width of the cup across the constriction just above the base is 

 20 mm. A very slender example is 82 mm. in length, 30 mm. in diameter at 

 the aperture, 11 mm. at its narrowest point and 13 nmi. across the ba.se which 

 is not entire. In still another specimen, which may be somewhat compressed 

 vertically, the length is but 20 mm., the diameter of the aperture 27 mm., and 

 that of the base 25 mm. In an individual about 50 mm. in length and having 

 a basal diameter of 25 mm., the basal expansion or frill has a diameter of about 

 17 ram. A single example surpasses the usual dimensions of the species, 

 presenting a length of 175 mm. and even thus incomplete. 



Localities. In the upper arenaceous beds of the Chemung group at Wells- 

 ville, N. Y. This usually small species has been found here by Mr. E. B. Hall 

 in considerable quantities. About fifty specimens, all from the same spot, have 

 been examined and these we are informed represent but a small part of 

 the number there obtained. It also occurs at Scio, Allegany county, Ischua, 

 and Olean, Cattaraugus county, and has been found on the Cassadaga creek in 

 Chautauqua county. 



TlIYSANODICTYA P(ECILU8, Sp, nOV. 

 Plate xxiv, Figs. 10, 11. 



Sponge somewhat variable in form ; short and robust or long and slender ; 

 subcylindrical, contracting above the base for less than one-half its length, and 

 again expanding to the aperture, whose diameter is about equal to that of the 

 base. Basal disk very depressed, almost flat; margins thickened and also 

 extended into a peripheral frill. 



Reticidihm having the general expression of that in ThusaiUKlidya rudis, 

 though the elongate rectangular primary quadrules are regularly smaller, each 

 comprising four parallelograms measuring on an average 4x6 mm. At the 

 base and near the aperture these areas are more nearly square. The pri- 

 mary spicular bands are sharply elevated, minutely nodose at their extremi- 

 ties upon the external cast, and both the vertical and horizontal series 

 are carried out into broad, erect lamellae which have a diameter of from 



