44 University of Washington Publications in Geology [Vol. I 



appearance of this species is somewhat similar to C. cowlitzensis Weaver, but 

 the spire of both young and mature individuals of C. vaderensis is only about 

 one-half that of C. cowlitsensis. The former possesses also a characteristically 

 greater diameter. 



Dimensions. Altitude of shell 29 mm. ; width of body whorl 12 mm. ; apical 

 angle 60. 



Occurrence. At locality 329 (University of Washington Palaeontological 

 Collection) at bend of Cowlitz River, near Vader, Lewis County, Section 28, 

 Township 11 North, Range 2 West. 



GENUS GONIOBASIS 



GONIOBASIS HANNIBAU n. Sp. 



Plate XII, Figures 2, 3 



Description. Shell medium, thin and polished; elongate- conic in shape; 

 whorls probably eight, specimens usually broken at fourth or fifth whorl ; sides 

 of the whorls very slightly convex; suture linear; aperture subovate, produced 

 below, not sinuated but widely united at the anterior end. Surface ornamented 

 with from sixteen to twenty vertical ridges or plications which are developed 

 in parallel waves over all the whorls ; crossing the longitudinal ribs there are 

 usually six spiral lines or ribs with interspaces half their width; at the inter- 

 section of the vertical and spiral ribs fine nodes are produced which give the long- 

 itudinal ridges a beaded appearance ; the vertical riblets do not continue over the 

 basal portion of the body whorl, that region ornamented by spiral lines only. 



The decoration of this shell is extremely variable. The extreme form 

 in sculpture has been taken for the type of the species. Goniobasis olequahensis 

 (Arnold and Hannibal) represents the smooth type of shell. A large amount of 

 material collected of this species contains specimens of all stages of sculptural 

 development. The smooth shells reveal on the lower whorls only fine wavy, 

 oblique lines ; many shells have oblique, longitudinal, plications on the nuclear 

 whorls which may be absent on the lower whorls. The occurrence of the spiral 

 ribs is not definite, they may occur on one whorl and not on the others ; they may 

 be present on the upper portion of a whorl or whorls, or they may occur only on 

 a portion of one or several whorls. The occurrence of the spiral band or line just 

 below the suture is not a constant character, and on the lower portion of the body 

 whorl there may or may not be a set of spiral lines. The figured specimens of this 

 species (PI. XII Figs. 2, 3) illustrate a difference in sculpture. The collection 

 contains specimens which show transition stages between the two types of shell 

 as illustrated. 



