Marshall and Murdoch. — Tertiary Mollusca. 129 



row ol small nodules on the angle, thence take a backward sweep, and 

 vanish a little above the suture, on the anterior end of the last irregular 

 and here and there in the form of strong growth-striae ; spiral striae are 

 preserved in places only and difficult to detect. There is a narrow sub- 

 perforation at the side of the columella, bounded by a small funicular ridge 

 which curves around to the basal lip. Aperture oval, narrow above, basal 

 lip slightly produced and with a lightly impressed gutter at its junction 

 with the columella, inner lip with a thin narrow callus, columella slightly 

 curved and a little reflexed anteriorly. 



Length, 6'25 mm. ; width, 3-5 mm. ; length of aperture, 2*5 mm. 



Locality, Hampden. Collected by Dr. Marshall. 



Type to be presented to the Wanganui Museum. 



There is a single example only. It is very different from any other of 

 our Recent or fossil Rissoids, and it is with hesitation we refer it to the 

 genus. More material may be brought to light, possibly allied forms which 

 would lead to a more confident classification. 



Sella attenuissima n. sp. (Plate VI, fig. 2.) 



Shell partly embedded in the matrix, very small, gradually tapering, 

 and exceedingly slender ; whorls about seventeen, the protoconch of two 

 and a half whorls, smooth, apex minute oblique to the axis, the two 

 succeeding whorls well rounded and somewhat swollen, thence, flattened 

 and with three sharply-raised spiral cords, equal to or slightly narrower 

 than the grooves, the lower cord perhaps slightly the stronger ; the 

 spacing of the sculpture, including the sutural groove, is exceedingly uni- 

 form ; within the grooves and preserved in places only are microscopic 

 sharply-raised growth-striae ; the last whorl apparently with four or more 

 spirals, the anterior end obscured by the matrix. 



Length, 7 mm. ; width, 0'9 mm. 



Locality, Hampden. Collected by Dr. Marshall. 



Type to be presented to the Wanganui Museum. 



There is a single example only, characterized by its exceedingly attenu- 

 ated form. The protoconch in some respects approaches S. hulhosa Suter. 



Triphora aoteaensis n. sp. (Plate VI, fig. 3.) 



Shell small, slender, of twelve flattened whorls, excluding the apex, which 

 is missing. Sculpture : There are three rows of gemmules on each whorl, 

 a small undulating smooth threadlet at the suture above and occasionally 

 a very minute thread on the margin below, both absent on the earlier 

 whorls ; on the last at the basal angle is a' fourth smooth sharply -raised 

 narrow riblet, below this a more slender cord, and between the latter and 

 beak two or three ill-defined lines ; of the gemmules there are about 

 sixteen in a row, separated rather less than their own width and linked 

 within the rows, axial buttresses low and broad, forming oblique vertical 

 rows but not always continuous ; the lower row of gemmules is the most 

 strongly developed, the second distinctly smaller, equal to their own width 

 apart, the third separated by a narrow groove and much more feeble ; the 

 gemmules are somewhat oval in form, the anterior sides rounded, the 

 posterior rising rather abruptly, giving to them a subtruncated and slightly 

 ridged appearance. Base sloping, flattened ; distinct growth-striae form 

 small irregular riblets. Aperture small, subquadrate, outer lip imperfect, 

 columella short, nearly straight, sharply bent and twisted at the anterior 

 extremity. 



5 — Trans. 



