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University of California Publications in Geology [Vol. 8 



Genus Argobuccinum Morch 



ARGOBUCCINUM ARNOLD I, n. sp. 

 Plate 21, figures 4a and 4b 



Shell moderately large, thin, fusiform, with seven or eight strongly 

 sculptured whorls; spire prominent; apex defective in the type, whorls 

 of the spire convex, constricted at the sutures, sculptured with about 

 fourteen sharply rounded arcuate, raised axial ribs and seven or 

 eight thread-like spiral grooves ; the axial ribs are strongly raised at 

 the periphery and extend almost from suture to suture, becoming 

 obsolete near the posterior margin, producing a constricted sutural 

 band ; the spiral grooves are usually shallow and are most pronounced 

 at the periphery; the area between the two grooves is strap-like and 

 finely striate, producing obscure nodulations on the axial ribs ; suture 

 distinct, appressed; varices similar to the ribs, slightly larger, about 

 two to the whorl ; body-whorl ventricose, subtabulate, shoulder well 

 rounded, sculptured with fifteen axial ribs and about fourteen spiral 

 bands ; on the anterior half of the whorl the axial ribs are obsolete, 

 the spiral bands raised and equal in width to the interspaces; on the 

 posterior portion the axial ribs are pronounced, the spiral bands broad 

 and inconspicuous and separated by narrow grooves; aperture ellipti- 

 cal; outer lip thin; inner lip crossed by the spiral cords; canal short. 



Dimensions. — Length of the type, 70 mm. ; maximum diameter, 

 45 mm. ; length of the aperture, 35 mm. ; width of the aperture, 

 20 mm. 



Occurrence. — Five specimens of this species were obtained from 

 the upper Miocene at the mouth of Bear River, Humboldt County, 

 California. University of California Locality 1863. 



This species somewhat resembles Argobuccinum cammani Dall, 

 from the Empire Beds of Coos Bay, Oregon. The characters which 

 distinguish it from the latter are the spiral grooves on the spire and 

 on the posterior portion of the body-whorl, instead of the raised spiral 

 bands which are found on A. cammani Dall. 



AEGOBUCCINUM SCOTIAENSIS, n. sp. 

 Plate 21, figure 3 



Shell large, fusiform, thin, with rather rapidly enlarging whorls 

 which are crossed by two inconspicuous varices ; whorls convex, 

 evenly rounded; sculpture reticulate, consisting of elevated spiral 



