NArTILID3i. 
85 
but less conspicuous, revolving strite or low ridges, are often pre- 
served over the ventral face of the shell, while a single specimen 
preserves the marks of obsolescent, low undulations, as in some 
specimens of X. subliratus. In another specimen, near the aper- 
ture, there is a belt more than twenty mm. wide, which is strongly 
marked by rounded, transverse undulating strice, the undulations 
being caused by slender revolving strice, of which there are six or 
seven in the space of five mm. 
“ The internal cast is essentially smooth and polished (this 
feature being due to the nature of the matrix), with the exception 
of the suture lines, the impressions of the transverse striiTe, and the 
obscure radiating strice, and obsolescent undulations. The largest 
individual observed has a diameter of about 200 mm., as measured 
across the volutions at the base of the grand chamber ; the entire 
individual has been much larger. 
“ This species has its nearest relations with X. maximus, and 
possesses many features in common with that form. With a single 
exception all the specimens are laterally compressed, and this may 
conduce to the contraction of the umbilicus and the apparent re- 
entrant character of the volutions which is observed in comparison. 
The specimens are preserved in a soft, fissile black shale, and the 
surface markings are more distinctly retained upon the cast, or 
upon the adhering inner lamina) of the shell, than in X. ma.vimvs, 
which is usually imbedded in a coarser material. The pitted and 
mammillary deposit, which everywhere marks the exfoliated speci- 
mens of X. meuvimus, is either entirely absent, or scarcely at all 
observable on the specimens of X. oriens. 
“ This form is distinguished from X. marjisfer by its comparatively 
wide umbilicus, the greater exposure of the inner volutions, tho 
nearly circular transverse section, and sinus in the aperture. The 
surface-markings and the absence of nodes on the ventro-lateral 
margins are distinctive features.'*’ (Jfall.) 
Eemarls. The individual representing this species in the British 
Museum, though much crushed, shows with sufficient clearness the 
characters described by Hall. The septate portion only is pre- 
served. 
Horizon. Hamilton Group (Middle Devonian). 
Locality. Hew York State. 
Represented in the Collection by a single example. 
