Vol. IV] DICKERSON— SIPHON ALIA ZONE, OREGON -j^^j^ 



R. 3. W., on the east bank of Little River at its confluence with 

 the Umpqua, underneath the bridge at that point. Coll., Bruce 

 Martin. 



Named for the type locality of the species. 



CERITHIOPSIS OREGONENSIS, new species. 



Plate 11, figures 5a and 5b. 



. Shell elongate conic; upper whorls missing; remaining 

 whorls, except the body-whorl, marked by three strong, equally 

 spaced spiral lines of same strength crossed by axial ribs, the 

 crossing being marked by rounded nodes; a very fine thread 

 found between the spiral lines ; suture impressed, linear ; body- 

 whorl marked by four rows of nodes instead of three, as in 

 the spire-whorls, the last row being weaker than the others ; 

 fine threads between these spiral lines; base marked by four 

 or five nodose spiral lines and threads, the spiral lines being 

 smaller than those on rest of whorl; aperture ovate-quadrate, 

 with narrow anterior sinus ; outer lip thin ; canal twisted. 



Dimensions ; Length of broken type, 20mm ; width of body- 

 whorl, 4.5mm. 



This species resembles C. alternata Gabb in shape, but its 

 whorls are nearly flat while those of C. alternata are decidedly 

 convex. The nodes are much stronger than on C. alternata. 

 It differs from C. excelsus Dall in that its whorls are nearly 

 flat and its spiral lines less numerous and larger. 



Type: — No. 246, Cal. Acad. Sci. Locality 25, Roseburg 

 Quadrangle, Oregon, near the center of Sec. 19, T. 26 S., R. 3 

 W., on the east bank of Little River at its confluence with the 

 Umpqua, underneath the bridge at that point. 



Named for its occurrence in the Eocene of Oregon. 



SIPHONAUA CLARKI, new species. 



Plate 11, figures 4a and 4b. 



Shell fusiform, with high spire; nine whorls; spire-whorls 

 distinctly shouldered and decorated by about nine rounded 

 nodes which exhibit two apices where two strong spiral lines 

 cross them ; space between appressed wavy suture and shoulder 

 concave, and covered by about ten spiral threads ; flat space be- 

 low the suture marked by two strong spiral lines and by eight 

 to ten spiral threads, this area parallel to the axis of the shell ; 



