Rissoina.] GASTROPODA. 223 



pointed. Whorls 5, lightly convex, the last large, occupying nearly 

 three-fourths of the total height, slightly flattened below the suture. 

 Suture superficial, submargined above. Aperture vertical, pyriform, 

 truncated at the base. Outer lip strong, descending nearly straight, 

 then turning at a narrowly rounded angle toward the straight and 

 slightly notched basal lip. Columella concave and truncated below. 

 Inner lip forming a strong but narrow callus on the body-whorl, 

 broadening above, where it joins the outer lip ; on the columella it is 

 much narrower, covering only the inner half of it. Operculum un- 

 known. 



Diameter, 1-5 mm. ; height, 3 mm. 



Type, from the Pliocene, in the Canterbury Museum, Christchurch. 



Hob. Near Channel Island, Hauraki Gulf, in 25 fathoms ; near 

 Little Barrier Island, in 20 fathoms (R. H. Shakespear) ; near Cuvier 

 Island, in 38 fathoms (Captain Bollons) ; Queen Charlotte Sound, in 

 16 fathoms (Captain Bollons) ; off Otago Heads, dredged (A. Hamil- 

 ton) ; Purau, Lyttelton Harbour, and Lyall Bay (Iredale). 



Fossil in the Pliocene. 



Subgen. 1. EATONIELLA, Dall, 1876. 



Eatoniella, Dall, Bull. U.S. Nat. Mus., iii, 1876, 42. Type: R. kerguelensis, 

 Smith. Eatonia, E. A. Smith, 1875 ; not of Hall, 1857. 



Shell smooth, aperture subcircular, peristome simple, continuous, 

 not effuse below, lip-margin not thickened ; operculum paucispiral, 

 with an interior claviform process. 



KEY TO SPECIES. 



A. Spire but little higher than the aperture ; shell thin, pellucid, 



microscopically very finely spirally striate . . . . cuvieriana. 



B. Spire about 1 \ times the height of the aperture. 



a. Shell with white spots and zigzag lines below the suture ; 



rimate . . . . . . . . . . . . limbata. 



aa. Shell without any colour -mar kings, black ; not rimate . . Chiltoni. 



C. Spire about twice the height of the aperture. 



a. Shell fairly solid, opaque, peristome lightly thickened . . olivacea. 

 aa. Shell thin, semitransparent, with a brown band below the 



suture ; peristome thin and sharp . . . . . . fuscozona. 



8. Rissoina Chiltoni, Suter, 1909. Plate 13, fig. 15. 



Rissoina Chiltoni, Suter, Subantarct. Islds. N.Zeal.. i, 1909. 18, pi. 1, 

 f. 2. 



Shell minute, elongated conic, imperforate, rather solid, smooth, 

 black. There is no sculpture ; the surface in most specimens much 

 corroded. Colour black, peristome white, interior of aperture bluish- 

 black. Spire conic, obtuse, its height about 1^ that of the aperture ; 

 outlines straight. Protoconch somewhat globular. Whorls 5, regularly 

 increasing, very lightly convex ; base rounded. Suture not much 



