CEPHALOPODA OF THE EOCENE MAELS. 287 



Genus ATURIA Bronn. 



Aturia Vanuxemi. 



Plate XLix, Figs. 1, 3, and Plate L, Fig. 1. 



Pelagus Vanuxemi Conrad: Jour. Acad. Nat. Sci., vol. 1, 2d ser., p. 130, PI. xiv, 



Fig. 15. 

 Aturia Vanuxemi Conrad: Am. Jour. Conch., vol. 2, p. 15. 

 Aturia ziczac (Sow.) Conrad: Am. Jour. Conch., vol. 1, p. 150; Smithsonian 



Check List, p. 19. 

 Nautilus angustatus Con.: Am. Jour. Conch., vol. 1, p. 150; not N. angustatus 



Conrad, U. S. Expl. Exp. Geology, p. 728, PI. xx. Figs. 5, 6. 



Shell of moderately large size, the most perfect one which I have seen, 

 but which is an internal cast only, measures 6J inches in its longest diame- 

 ter, and has a thickness from side to side of about 2 inches, but has appar- 

 ently been considerably compressed in this direction. The form is closely 

 convolute with a closed umbilicus; sides depressed, convex, and dorsum 

 narrowly rounded. The inner volution projects into the aperture of the 

 outer one about two-fifths of the distance from the umbilicus to the outer 

 margin, leaving the aperture, in this laterally compressed specimen, some- 

 what elongately halbert shaped. The septa are somewhat closely arranged 

 and number about sixteen in the last coil of the shell. In rising from the 

 umbilical depression they make a broad forward curve or arch, which 

 extends to a little beyond the middle of the width of the volution, from 

 which point they are bent abruptly backward, and form a proportionally 

 long, narrow, and somewhat pointed spur, the outer edge of which is 

 straighter than the inner and with that of those in the rear and in advance 

 form a nearly straight and continuous line parallel to the margin of the 

 dorsum. After this edge of the spur reaches a point about opposite the 

 place of abrupt flexure of the inner side, the line runs straight across the 

 back of the volution, forming a broad projecting lip on the back of the 

 shell equal in length to that of the spur on the side of the volution. The 

 spur on the side, rather outside of the middle of the volution, with the point 

 reaching almost to the corner of the outer lip of the septum below, is a 

 rather well marked feature and somewhat characteristic. Septa deeply con- 

 cave, as seen in an apertural view. Siphon large, situated fully its own 



