JEFPEEYSIA. 389 



ovarium, when present, between the lobes, are very conspi- 

 cuous through the tenuity of the shell. 



The animal is not shy; it shows the organs freely and 

 marches with vivacity ; it also swims and floats with perfect 

 ease, as is usually the case with all the smaller and shorter 

 Chemnitzia. It has frequently occurred in the quiet half- 

 tidal pools at Exmouth. 



? J. OPALINA, nonnull. 



? J. opalina, Brit. Moll. iii. p. 154, pi. 76. f. 3, 4, & iv. p. 267, pi. 133. 



f. 6 ; (animal) pi. M.M. f. 2. 

 J. globularis, Brit. Moll. iv. p. 268, pi. 133. f. 5. 



Live specimens of the beautiful so-called Rissoa opalina 

 were received in a bottle of sea-water, from my friend 

 Mr. George Barlee, at Falmouth, whose laborious and painful 



journeyings 



" per omnes 



Terrasque, tractusque maris," 



of the wilds of the Ultima Thule and Hebridean seas, have 

 enriched science with so many rare and interesting objects ; 

 the present one is invaluable, as it clears up several doubtful 

 questions which might long have remained unexplained, if 

 this curious animal had continued to escape observation. 

 Though somewhat torpid, I have observed the organs, an 

 account of which, I am sure, will gratify many of my readers. 

 There is no recorded description of the animal. 



Animal inhabiting a spiral, smooth, thin, white, subglobose 

 shell of three volutions. Mantle of the palest azure, slightly 

 canaliculated, otherwise even with the shell. The head is a 

 rounded, short, contractile, proboscidiform muzzle, which is 

 rarely carried beyond the foot and tentacula ; it is vertically 

 cloven at the terminus and under part, and furnished with a 

 pair of subcircular jaws and lingual riband, which in several of 

 the examples I frequently saw protruded after the manner of 

 the Rissoce ; the head and neck are brindled with fine dark 

 lead-coloured lines. 



There are a pair of tentacula on each side the neck behind 

 the muzzle, springing from a distinct common origin or 



