4G2 PELORID.E. 



sion, exactly as in Murex tubercularis, but not quite so de- 

 cidedly : it is probable that tliis groove, and apparent, if not 

 real, solution of continuity, is not solely to convey water to 

 the foot, but also to assist the folding of that organ on its 

 anterior portion, and the central pit is to aid another doubling 

 at right angles. I witnessed the operation both in retraction 

 and when the animal deployed the foot, which confirmed that 

 part of M. Bivona's description, " Pes, plica triplici in testam 

 retractus." On retraction, each posterior longitudinal half, 

 bounded by the groove, is folded on its counterpart, forming 

 two plications ; then these halves are at the central depression 

 doubled on the anterior portion, and the whole is withdrawn 

 and covered by the operculum. Of course the routine of ex- 

 sertion is exactly the converse, but it appears to me that these 

 manoauvres are pretty much the same in all the Gastero- 

 poda. Scalaria, in these and other points, is closely allied 

 to Murex tubercularis, as far as external organs are consi- 

 dered ; it only differs in having a spiral operculum instead of 

 a muricidal one. 



This creature is very free in showing its peculiarities. It 

 inhabits the three zones. The one described was captured by 

 myself in the middle of the littoral district, at the roots of the 

 Corattina vfficinalis, at Exmouth, where it is of rare occurrence. 

 I have not taken more than five or six live specimens of this 

 species and the S. communis in thirty years ; most of them 

 were from the coral zone. I observed that when the animal 

 was in extremis, it emitted, like the lanthinte, a brilliant purple 

 fluid. I am not prepared to speak, at present, of the repro- 

 ductive organs and the internal mechanism of the proboscis, 

 but we may safely conclude that it does not greatly differ 

 from the Buccinum undatum, Murex with me. I have exa- 

 mined the S. communis, which does not vary in its organs 

 from this species; in its colours and the disposition of its 

 markings it exhibits some differences. 



I believe the only other British species are the S. TreviUi- 

 ana, S. Grcenlandica, and S. Turtoni. The first two I have 

 not seen alive ; the latter has been examined, but I unfortu- 

 nately lost the notes. I have omitted to state as one of the 



