PYRAMIDELLIDA. 405 
been the arena and one of the great laboratories of the species- 
manufacturers, who have turned them out with a liberal hand. 
This has in some measure been occasioned by the singular 
variations exhibited by the individuals of almost every species 
of the genus. 
I here offer a correction. When I stated in the ‘ Annals of 
Natural History’ that all the Chemnitzie had a similar apo- 
physis in the operculum to that assigned by Mr. Alder as one 
of the distinguishing characters of the genus Jeffreysia, I 
thought my discovery a new one; but I find by Dr. Johnston’s 
excellent ‘ Introduction to Conchology,’ from a paper inserted 
therein, written in 1835, by John Edward Gray, Esq., that 
that gentleman is the original discoverer of the flap or 
process in the opercula of the Pyramidellide. 1 now pre- 
sent a most important quotation from that portion of the 
paper relating to the opercula (p. 449); Mr. Gray says,— 
“The opercula of some shells which have plaits on their pillar 
are very thin, and are furnished with a moveable flap on the 
left side of their anterior margin, which passes over the plaits. 
I first observed this in the common Tornatella, and after- 
wards in Turbo pallidus of Montagu, the genus Odostomia 
of Dr. Fleming, and have since verified it in Pyramidella. 
The subannular operculum of Turbinella cornigera has a 
notch in the middle of the anterior margin and a plait 
running from the nucleus, but in this case the flap is not 
moveable.” 
The latter part of Mr. Gray’s remarks with reference to the 
subannular operculum, the plait running from the nucleus, 
and the flap not being moveable, precisely embrace my views 
of Jeffreysia diaphana, in which the flap, as Mr. Gray calls it, 
is not moveable; and I found that to be the case in most of 
the fourteen species of Chemnitzie I have examined; but in 
some, for instance the young shells of Chem. pallida, and in 
Chem. rufa, the flap or apophysis is moveable, or im other 
words, it is cartilaginous and flexible. 
The aspect of the Chemnitzian animal is so peculiar and 
impressive, that when once it has been seen it will never be 
forgotten, and the malacologist will instantly detect an indi- 
