16 A MONOGRAPH OF 



20. — Helix ( ) positura — Cox, 



Legrand's Col. for Mon., sp. 42, pi. ii., fig 10. 



Shell very narrowly umbilicated, conoidly depressed, thin ; of a dull 

 chestnut-brown colour, with strongly marked but widely separated costoe, 

 more prominent above than below ; whorls 4, gradually increasing in 

 size, last expanded, sub-carinated, not depressed in front ; aperture 

 slightly angled, lunately-rounded _, peristome simple, thin ; margins 

 approached, columellar margin dilated and reflected over the umbilicus. 



Diameter, greatest 0*25, least 0*18 j height, O'l'J of aninch. 



Habitat. — Kecherche Bay. 



A small sub-carinated shell, with prominent striae. I have examined 

 the type and other specimens, and I am convinced that it is but a young 

 meadianus ov AUporti, wanting the last whorl, in which the striae is more 

 than usually prominent, which is often the case, as also in the typical 

 H. Fordei. Retained for further investigation. 



21. — Helix) ) c^esus — Cox. 



Legrand's Col. for Men., sp. 21, pi. i., fig. 4, 

 H. occuUus — Cox. 



Legrand's Col. for Mon., sp. 23. 



Shell deeply, openly, rather narrowly umbilicated, globosely- 

 depressed ; spire rather raised ; thin, light, reddish-brown ; whorls 5, 

 much rounded, the last slightly depressed in front ; base convex, exca- 

 vated round the umbilicus j surface slightly irregular with lines of 

 growth 3 aperture almost round ; peristome simple, not thickened ; 

 margins approximating ; columellar margin very slightly dilated. 



Diameter, greatest 0'18, least 0-05 ; height, 0-10 of an inch. 



Habitat. — Kecherche Bay, near Southport Lagoon, Table Cape, 

 islands in Bass Straits, Circular Head. 



The shells described as H. occidtus are the young immature specimens. 

 At Circular Head it is extremely abundant, gregarious among the rocks 

 surrounding the " Nut" to the seaward, with H. Stanleyensis and some 

 other small forms. It is somewhat remarkable that it has been col- 

 lected at the two extremes of the island ; at Becherche Bay it was found 

 associated with H. AUporti, and equally as profuse as at its northern 

 habitats. So far it has been observed only near the sea, so that it 

 may be considered peculiar to the coast. At Table Cape I observed 

 large numbers of dead bleached specimens, scattered about on the cliffs 

 with its usual northern associates and Succinea Australia. 



