184: University of California Publications in Geology [Vol. ll 



at right angles to the sides of the whorls ; this angulation stands out rather 

 prominently, giving the upper part of each whorl a collar-like appearance. Sides 

 of whorls slightly concave a little below the angulation on the body whorl ; below 

 this concavity the surface swells out rather strongly ; anterior to this it slopes 

 down obliquely to the canal. Surface eovcred by numerous spiral ribs, with 

 interspaces about as wide as ribs. On all the specimens at hand, this ribbing is 

 faint to obsolete on whorls of spire and on larger part of body whorl, but on 

 anterior end of body whorl it is rather strong. The faintness of the ribbing is 

 due, at least in part, to poor preservation and it is not unlikely that other 

 specimens may be found, on which it is fairly heavy over all or most of the shell. 

 Outer lip thin ; inner lip not exposed. Canal straight, medium in length. 



Dimensions. — Length, about 18 mm.; canal broken; height of spire, 7 mm.; 

 greatest width of body whorl, about 8 mm. 



Occurrence. — University of California locality 76. 



This form is of somewhat the same general type as Clavella sinuata 

 G abb, 100 from which it differs quite decidedly in the shape of the body 

 whorl and in minor details of sculpturing. Gabb, in his original 

 description of Clavella sinuata, determined it to belong to the genus 

 Clavella Swainson ; in the second part of the same volume he described 

 a new genus, Agasoma, the type of which is A. gravidum. He in- 

 eluded his species Clavella sinuata in that genus. The writer believes 

 that Gabb's original determination of the generic character of this 

 species was more nearly correct than the last ; it corresponds more 

 closely to Swainson 's genus, Clavella, 158 than to the type represented 

 by Agasoma gravidum. 



Family Volutidae 

 Genus MIOPLEIONA Dall 

 MIOPLEIONA sp. 

 Plate 23, figure 13 



Shell large, fusiform ; spire broken on type and not known from other speci- 

 men. Sutures appressed ; body whorl large, about twice as long as wide. Surface 

 of whorls gently convex, covered by numerous medium fine, longitudinal, irregular 

 undulations, which should possibly be considered as irregular lines of growth 

 rather than axial ribbing. Surface otherwise smooth. Aperture elongate, ellip- 

 tical ; outer lip thin ; pillar straight ; one fairly prominent pillar-plate observable. 



Occurrence. — University of California locality 1156. Only one imperfect 

 specimen of the form described above was found. It occurs in the same horizon 

 with M. indurata, from which it is apparently, though not certainly, distinct. 



lse For description of Clavella sinuata Gabb, see Geol. Surv. Calif., Palaeon- 

 tology, vol. 2, p. 5, pi. 1, fig. 7, 1866. 



158 The type of Swainson 's Clavella is C. serotina Hinds. See Tryon, Struc- 

 tural and systematic eonchology, vol. 2, p. 129, pi. 47, fig. 83, 1883. 



