462 PELORIDA. 
sion, exactly as in Murex tubercularis, but not quite so de- 
cidedly :—it is probable that this 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. JI 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 im 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doubled on the anterior portion, and the whole is withdrawn 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 
manceuvres are pretty much the same in all the Gastero- 
poda. Scalaria, i 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 
Corallina officinalis, 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, hike the Janthine, a brilliant purple 
fluid. Iam 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. Trevilli- 
ana, S. Grenlandica, 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 
