Spkcies op thk Ciiemuno Group. 135 



TlIYSANODIOTYA APLETA, Sp. nOV. 

 Platk XXVI, Fio. 1 ; Puitk xxvii, Fio. 8. 



This name is applied to incomplete examplew indicating cups of gi*eat size 

 with a very coarsely lamellose-reticulate surface. None of the observed speci- 

 mens is sufficiently complete to give a clear conception of the form of the 

 sponge or a decisive idea of the generic character of the species. 



One of the largest individuals seen is that figured on Plate xxvi ; this has 

 a length of about 275 mm. and a greatest width of 220 mm, The drawing has 

 been made from a plaster-cast of an external impression, which shows the 

 curvature of the surface and probably gives an approximately correct idea of 

 the diameter of the cup, but no accurate indication of its length. So far as 

 the original form of the cup is here suggested, it does not widely differ from 

 that of the known species of TnYSANODiCTVA. The character of the surface 

 fortifies this resemblance. The principal spicular bands form strong, erect 

 lamellae, nodose at their intersections, characters which indicate the surface 

 structure in that genus. The primary quadrules are usually square and 

 measure about 14 mm. on a side, though very variable both in fonn and size. 

 The secondary bands are usually clearly defined in all external casts, and no 

 internal cast has been observed showing the finer meshes of the reticulum. 

 The surface shows no other ornamentation than that described. 



Localities. The largest of the specimens of this species was found loose 

 among the sandstones of the upper Chemung at Alfred, Allegany county, 

 associated with Spirifer dlsjunctus. Others nearly as large have been 

 obtained at Hinsdale, Cattaraugus county, and fragments at Scio and Ischuji. 

 Smaller fragments have been received from Nile and Wellsville, localities 

 in Allegany county, and from Olean, Cattaraugus county. 



Thysanodiotya tukricula, sp. nov. 



Flats xxxviii, Figs. 6, 6. 



This is the most slender and graceful of all the species of the genus. The 

 sponge is small and either tapers or expands upward from a relatively broad 

 base. The surface is cancelled into narrow, elongate meshes which grow 

 shorter about the aperture. While these quadrules may belong to a minor 

 series, yet they are predominant upon the surface to the obscuration of othera. 

 The periloph is quite broad. These characters are well shown in the two 

 entire specimens figured, one of which has a length of 40 mm., a basal width 

 of 1 2 mm. and an apertural mdth of 7 mm. The width of the basal expansion 



