RISSOA. 379 



M. Loven would term it, " late vibr antes," beneath which it is 

 slightly constricted, and a little beyond the middle, posteally, 

 is fixed on a simple lobe without lateral expansions or terminal 

 cirrhal filament ; the light yellow suboval opercnlum with di- 

 stinct grossly-spiral turns, exactly as in the paucispiral Litto- 

 rinidce ; below the operculum the foot is visibly contracted 

 on each side, and terminates in a rounded, rather broad point ; 

 no median line is apparent in any part of the sole. 



This creature is not at all shy ; it remained lively for thirty- 

 six hours, and gave every facility for good examination ; it 

 readily creeps up the deepest glasses, and however often 

 brushed down, starts again with imabated vigour. The speci- 

 men described was detected in Littleham Cove, between 

 Exmouth and Budleigh Salterton, in the littoral level, in 

 debris of minute decayed shells mixed with sand and mud 

 that had an offensive odour, the mass being deposited on the 

 margins of deep quiet pools affording nutriment to certain 

 long, narrow, grassy sea- weeds. I have been thus particular, 

 to obviate difficulty to future naturalists, and I wish them 

 success in obtaining a live specimen with less trouble than I 

 have had. 



The habitat of this species is, I believe, strictly littoral ; its 

 associates are the Rissoa parva, R. striata, R. planorbis, nobis, 

 (Skenea planorbis, auct.), as these are found in the same mass 

 of spoil. 



That this is a Littorinidan and almost a strict Rissoidean 

 animal, allowing a trifling margin for specialty-variations, 

 admits of no doubt. It has no malacological community with 

 Turritella, Aclis, or Chemnitzia ; but as the muzzle is carried 

 in nearly a similar position as in the latter genus, the young 

 inalacologist must take care in so small an object not to 

 be misled by this circumstance, or by the centrality of the 

 eyes at the base of the tentacula : the veteran observer with 

 delicate and apt manipulation, patience, and good glasses, will 

 easily detect the vertically cloven disk and corneous jaws, 

 which, with the rissoid simple tentacula, will demonstrate that 

 this animal is merely an elongated Rissoa. 



