178 



Shell shaped like Art.-mn, im; , .val or fii-ilonn, with the 



spire prominent, but shorter than the hist \\lmH. Whorls angular 



or channel led in the vicinity nf llie suture. A pert nre long and nar- 

 r.)\v, rounded at base, the ooliunella concave, somewhat thickened, 

 without folds or teeth. Type ./I."//-/,,,,,,,,-;,/ Kon. 



This genus was proposed for fs>il tonns having the contour of a 

 slender, long-apertured Ada' on, but without folds upon the coluni- 

 ellar lip. Orbigny claims the date 1847 for .\ctnonhta, hut it was 

 not actually published in that year. Sec I'n.dr. Pal. Strat. I'niv., 

 i, p. lix. The genus has been restricted by .Meek, who removed 

 from it the peculiar groups Conactceon and Earnnm-ftum. 'The typical 

 forms extend from the Carboniferous to the Portlandian formation. 



The two recent species referred to the gen us 'are to be regarded 

 as very doubtful members of it. They are more likely to be an in- 

 dependent group of foldless Actceonidae near Bullina, than descend- 

 ants of this long extinct genus, the shells of which have a fades 

 quite different. 



A. EDENTULA Watson. PL 49, figs. 12, 13. 



Shell fragile, ovate, white, with a thin, chestnut-colored epider- 

 mis, a bluntish scalar spire, a largish mouth, inner lip untoothed. 

 Sculpture : Longitudinals there are very many close set minute 

 lines of growth, with here and there one much stronger than the 

 rest, which cuts in like a fault on the spirals, interrupting their con- 

 tinuity. Spirals there are many regular, but not sharp-cut nor 

 -tippled furrows which corrugate even the interior surface of the 

 shell : about 70 of these are on the body; about 20 on the penulti- 

 mate whorl. They are strongest toward the middle of the body- 

 whorl, and somewhat faint toward the upper suture ; the flat surface 

 between them which is about thrice their breadth, is. more or less 

 distinctly scored by a very faint furrow. Color opaque white, 

 covered with a thin, glossy chestnut-colored epidermis, which is a 

 little darker below the suture and on the base. Spire rather high, 

 roundedly and bluntly conical, scalar. Apex -lightly eroded, 

 but evidently blunt, large and slightly inverted. Whorls 5i, 

 somewhat convex, of rather rapid but regular increase: the last 

 i< loiiLT and cylindrical, with a rounded produced ha-e. Suture 

 oblique, strong; axially impressed rather than channelled. Mouth 

 long, transversely pear-shaped, narrowing very gradually ft] 

 open and rounded below. 



