62 



Descriptions of some New Species of South 

 Australian Marine and Fresh-water 

 Mollusca. 



By Professor Ealph Tate, F.L.S., F.G.S., &c. 



TRead October 5, 1886.] 



Plates IV. and V. 



Helix reteporoides, spec. nov. Plate v., figs. 14 a— c. 



Shell rather widely umbilicated, depressed, orbicular, thin ; 

 spire a little elevated ; whorls five, convex, separated by a 

 deeply-impressed or channelled suture ; last whorl rounded, 

 not descending in front, base convex ; aperture slightly 

 oblique to the vertical axis, subcircular ; peristome simple, its 

 margins disunited ; columella slightly reflected over the um- 

 bilicus, which is wide and perspective. The ornament consists 

 of regular, crowded, thin, elevated, equal ridges, and trans- 

 verse, equidistant microscopic striae in the intercostal furrows ; 

 the ridges are more distant on the spire whorls than on the last 

 whorl ; the transverse striae are more conspicuous on the base, 

 and the distance between them about equals the width of the 

 interstitial grooves. Colour of shell reddish-brown. 



Dimensions. — Major and minor diameters, 7 and (3*25 ; height, 

 4 ; diameter of umbilicus, 1*5 millimetres. 



Localities. — Black Hill, near Adelaide, under rotten stumps 

 of the " grass-tree" ; under stones at the foot of the cliffs at 

 the junction of the Hirer Para and Jacobs' Creek ; slopes of 

 Kaiserstuhl, Barossa Eange ; in the stringybark forests about 

 Clare and Penwortham. 



This species belongs to a group of small shells, more or less 

 depressed, and ornamented with raised lamellae, represented by 

 many species in Tasmania, with most of which I have compared 

 it, and by three described species in South Australia, but two 

 or more species yet remain undiagnostically known. As im- 

 plied by the specific name, the shell above described has affinity 

 with H. retepora (Cox), inhabiting the Flinders Eange (Masters) 

 and at Port Lincoln (JR. T.~) ; the general shape is the same, 

 but in H. reteporoides the spire is not quite so elevated, the 

 whorls more rotund, deeper suture, more convex base, larger 

 umbilicus, the costal lamellae equal and very much more 

 numerous, and the transverse striae finer. 



