336 NEW YORK STATE MUSEUM 



frequently present the aspect of being elevated vertically or in the direction 

 of the spiral. They are separated by smooth furrows in which, as they 

 become wider, new lines of tubercles develop, specially in later growth 

 stages. Tubercles and furrows are alike crossed by very fine oblique con- 

 centric striae, which occasionally become bunched together. On the very 

 early, one to three whorls, these concentric lines were sharp and distant 

 oblique ridges with no other ornament, thereon followed the introduction of 

 uninterrupted but strongly cancelated spiral ridges which gradually break 

 up into tubercles. In respect to ornament we may therefore note four well 

 defined stages, ( 1 ) embryonic, in which the shell (protoconch) is smooth, 

 (2) one to two and one half whorls, in which the ornament consists of 

 oblique ridges directed backward to the periphery (the character of the 

 periphery at this stage is not known, (3) two and one half to three and one 

 half whorls, in which continuous revolving ridges strongly cancelated by 

 the oblique ridges are introduced, and (4) the normal adult condition of 

 ridges broken up into disconnected parts or bands of tubercles. 



Dimensions. Average full grown specimens have a hight of 10 to 12 

 mm, a width across the base of 8 to 10 mm. 



Habitat. Genesee province ; Naples subprovince. Very common in 

 the soft shales through Yates, Ontario and Livingston counties. Also on 

 the Genesee river at the lower Portage falls and on Buck run near Mount 

 Morris. Chautauqua subprovince : near the eastern boundary of this 

 region the shell has been found in some abundance at Java Village, 

 Wyoming co. as fine barite replacements, at Cattaraugus creek near Ver- 

 sailles, Cattaraugus co., and also on the Lake Erie shore between Irving 

 and Dunkirk. The species has also been found to range high in the 

 Genesee valley, reappearing after the first introduction of the Chemung 

 fauna with Spirifer disjunctus (Scott's ravine, Fillmore, Allegany 

 co.) and also in the brachiopod fauna (Westhill flags) above the Naples' 

 fauna in the Naples section and eastward in the Seneca lake meridian. 

 It likewise occurs above the horizon bearing the Naples fauna, near Deer 

 Park, Garrett co. Md. 



