69 
to dislodge a specimen which showed the operculum actually 
lying in, or close to, the mouth of its parent shell, which was 
the not unfamiliar Hwomphalus sculptus of Sowrrsy, one of the 
classic species of Wenlock age. I incline to the belief that 
such fossils cannot be so very rare as some may suppose. It is 
more likely that hitherto they have been misinterpreted—that 
is, regarded as Discina, or as portions of a coral, and so forth, 
for to the former it bears more than a passing resemblance. As 
giving some colour to this, I have, just before preparing this 
account, had sent me by a brother naturalist, Mr. G. F. 
Wuuvsorne, M.A., F.G.8., four specimens from his collection 
for examination. These he had labelled “Discina,” but all 
of them proved on inspection to be the opercula of species of 
Euomphalus. They were obtained from near Malvern. In one | 
specimen the operculum was deeply withdrawn into the body- 
whorl of the shell, and not merely reposing near the mouth like 
one of my own specimens. Mr. Wur1pporNe acutely suggests 
that the occurrence of opercula might be useful in measuring 
the rate of deposition of sediment, and that a bed containing a 
number of shells without their opercula might be an argument 
against sudden deposition of sediments. A proper discussion 
of such observations, though of service, would exceed the limits 
of this paper. The presence of the operculum in or near its 
shell would naturally point to a state of undisturbed ooze or 
mud, and the absence of drifting currents. Where, on the 
other hand, the shells are found without their opercula, we might 
reasonably infer that the causes of the separation of the parts 
might be sought in violent eddies, or even in the thrust of the 
shaly beds after deposition of the sediment. 
In an additional specimen which I got from the May Hill 
beds, and which I thought was an operculum fixed in the mouth 
of a kindred species—the Huomphalus rugosus, I was not so 
fortunate, as Dr. H. Woopwarp, of the British Museum, on 
having the fossil cleared, found the object to be simply the 
hypostome of a trilobite—an Illeneus. This I mention by way 
of caution against similar illusions. However, even in the 
authentic examples—those of Huomphalus sculptus, the part in 
