160 GASTROPODA. [Aspidobranchia. 



Hab. Near Channel Island, Hauraki Gulf, in 25 fathoms (type), 

 near Little Barrier Island, in 20 fathoms ; Lyall Bay ; Snares, in 

 50 fathoms (Captain Bollons). 



Remarks. This species is nearly allied to C. Tatei, Angas, from 

 South Australia ; but the latter is larger, has a more elevated spire, 

 the spiral ridges are less numerous, more distant on the upper side, 

 and the interstices are ornamented with close fine and oblique radiate 

 striae, a feature totally absent in our species, there being only faint 

 growth-striae. 



Genus 3. CYCLOSTREMELLA, Bush, 1897. 



Cyclostremella, Bush. Trans. Connecticut Acad., x, 1897, 140. iType : 

 C. humilis, Bush. 



Shell minute, thin, semitransparent when fresh, planorbiform, of 

 few convex whorls, nearly symmetrically coiled, forming a concavely 

 depressed spire and large umbilical cavity. Epidermis thin, nearly 

 colourless. Nuclear whorl relatively large, smooth, turned downward, 

 seen only in a basal view, leaving a small pit above. Suture deep 

 and channelled. Aperture triangular-ovate, expanded below, angu- 

 lated above, with a relatively wide deep sinus just below the suture. 

 Peritreme thin, simple, continuous, not modified, slightly attached. 

 The operculum is very thin, almost colourless, broad-ovate, with the 

 nucleus below the centre and represented by a small smooth space 

 indefinitely defined by an indistinct line ; from this arise numerous 

 raised lines in the direction of the lines of growth, which are at first 

 near together, but diverge toward the outer margin, where they ter- 

 minate just within the edge ; others arise between these, about two- 

 thirds their length. 



Distribution. The type is from about 16 fathoms, off Cape Hat- 

 teras, North Carolina. A second species, C. californica, Bartsch, has 

 been recorded from the California!! coast. 



1. Cyclostremella neozelanica, Suter, 1908. Plate 34, fig. 9J 

 Cyclostremella neozelanica, Suter. P. Mai. S., viii, 25, pi. 2, f. 12. 



Shell small, planorboid, radiately ribbed, broadly umbilicate. Sculp- 

 ture consisting of close, sharp, radiate riblets, the smooth interstices 

 of about the same width as the riblets ; they are finer and closer 

 together near the aperture. Colour white. Spire sunken. Proto- 

 conch very minute, of about 1 whorl, turned downward. Whorls 3, 

 regularly increasing, leaving the apex considerably lower than any of 

 the succeeding volutions, the last being the most elevated, and having 

 a rounded periphery ; base convex, very broadly and openly um- 

 bilicated. Suture strongly impressed. Aperture circular. Peristome 

 discontinuous, thin. ColumcUa short, arcuate, not thickened ; the 

 converging margins of the peristome connected by a thin parietal 



