REPORT OF THE STATE PALEONTOLOGIST I903 29 1 



to the millimeter, run backward from the suture and each keeps 

 approximately in the plane of its origin till it terminates on the 

 columella. 



Observations. The apical angle of the shell in its two whorl stage 

 is considerably over ioo°, and becomes reduced to about 80° on the 

 completion of the third whorl; on certain lines the fourth whorl 

 rather increases this angle and so makes the outline across three 

 whorls from shoulder to shoulder slightly concave. The revolving 

 keels appear in the second whorl. 



The earlier portions of the suture are a little more angulated, but 

 acceleration seems to have carried back toward the apex the peculiar 

 feature of making the suture appear as one of the grooves. 



The slight flattening of the upper surfaces of the whorls and the 

 very marked obliteration of the suture by turning it into a groove 

 so very like the others may have served to make the shell less readily 

 distinguishable, as such, to the primitive perceptive powers of some 

 important enemies. 



The introduction of the new keels and the widening to which they 

 must have been subjected during the probable inflation of the base 

 of the whorl and the rounding of the aperture suggests that the 

 grooving of the upper portion of the whorl was later carried to the 

 base of the last half of the body whorl. This change was probably 

 induced by a changing in the position of the heavier shell during 

 locomotion or rest, and enabled the possessor to still present the 

 peculiar grooved aspect whatever may have been its purpose. 



This shell also seems to recapitulate in its ontogeny some interest- 

 ing features of its very remote history and at the same time, when 

 compared with modern shells, to show quite as remarkable an ac- 

 celeration as many of these; the name epitome therefore is suggested 

 as an appropriate one. 



Eunema altisulcatum sp. nov. 



Plate 5, figure 3 



Description. Shell small, turbinate, pyramidal, apical angle 52°, 

 hight 6mm. Whorls four, uniformly increasing in size, hight and 

 width of body whorl to total hight closely in ratio of 3 15 ; three 



