250 PALyEONTOLOCiY. 



under consideration shows this feature on several specimens in the collection 

 in a somewhat remarkable degree. The flange widens and is somewhat 

 roundly pointed in some cases near the beak, and gradually narrows 

 below. The general form of the shell is obliquely ovate, widest below, 

 varying much, however, in different examples. The substance of the shell 

 has been thin, and marked by comparatively strong concentric undulations, 

 but without other surface-characters. 



Mr. Meek's figures are true in all respects, except in wanting the 

 flange-like border ; and the figures given on plate 3 are for the purpose of 

 illustrating this feature. The species has considerable resemblance to L. 

 fragllis — Avicula fragilis HsiW (Greol. 4th Dis. N. Y., 1843, p. 222, figs. 1-2) 

 (fig. 2, he. cit, falsely represents a posterior wing), from the Genesee slate 

 and Portage group of New York, but differs materially in the greater elonga- 

 tion of the valves. Examples could, however, be selected from among the 

 New York collections that would exceed in length the shorter form from 

 the black slates of the White Pine District, while the peculiarity of having 

 the flange widening near the beak is a feature noticed only in- that species 

 among all of those recognized in the New York formations, and is one that 

 shows the close relations of the two species. The greater proportional 

 length of the shells of this one will serve to distinguish them. 



GASTEROPODA. 



Genus BELLEROPHON Montf. 



Bellekophon Neleus n. sp. 



Plate III, figs. 18-20. 



Shell rather above the medium size, nearly globular in form, a little 

 wider than high. Volutions rounded and very slightly carinate on the 

 back, the keel showing only as a low, rounded, scarcely elevated band on 

 the internal cast. Lip somewhat expanded laterally, the outer axial margin 

 forming a strong auriculation on each side of the shell ; margin of the lip 

 bilobed, deeply and broadly notched in the middle ; the sides of the notch 

 moderately expanding at first, but more rapidly above ; lobes of the lip 

 rounded. Umbilicus closed, but on the internal cast showing as of consid- 



