180 FroceedtiKjs of the Royal Society of Victoria. 



Outer lip with accurate margin and relatively strongly 

 thickened within, ascending well up the penultimate whorl, and 

 forming a well developed, deep and broad posterior canal. 



Inner lip furnished with about seven minute plaits, the 

 anterior one being the strongest and forming an obliquely 

 twisted plait, the successive posterior ones gradually diminishing 

 in size until they become mere denticles near the posterior end 

 of the aperture. 



Dimetisions. — Length, 2 mm. ; breadth, 1-5 mm. 



Locality. — Shoreham beach. Western Port Bay. 



Marginella alternans, sp. nov. (PI. XX., Fig. 3.) 



Description. — Shell very minute, sub-cylindrical, or somewhat 

 Cylichna-like, relatively thick, and opaque white, with a totally 

 immersed spire, and a flatly-convex body-whorl. Aperture long, 

 narrow, and ascending to the apex of the shell, and rather 

 everted at the extremity. Outer lip thickened and well margined 

 from the apex right down to the columella, where it coalesces 

 with the anterior columellar plait. Columella bearing about 

 four fairly strong oblique columellar plaits, the anterior being 

 the strongest and most oblique, with three much fainter inter- 

 mediate plaits between the stronger. 



Outer lip apparently smooth within. 



Dime7isio7is. — Length, 1-5 mm. ; breadth, 1 mm. 



Locality. — Shoreham beach. Western Port Bay. 



Observations. — The above specific name has been chosen on 

 account of the alternately large and small plaits on the 

 columella ; and we are not aware of any other Australian species 

 which is sufficiently closely allied to the present foim to call 

 for any special comment. 



Marginella flindersi, sp. nov. (PI. XX., Fig. 4.) 



Description. — Shell veiy minute, narrowly ovate, thin, shining, 

 white and translucent, with a totally immersed spire. 



Body whorl long, narrow, and very slightly though regularly 

 convex. 



Aperture long, narrow, and ai-ched from the extreme posterior 

 to the extreme anterior, and at the posterior end is a deep and 

 somewhat effuse canal. 



