a7 
ORGANISMS FROM THE RECENTLY DISCOVERED ROMAN BATH. 195 
molluscs. In the second family of this order, Paludinide, most of 
the shells in the deposit are found Genus 2, Bythinia, species 
Tentaculata. In the living creature the tentacles are filiform, and 
the shells, when thoroughly cleaned, are beautifully transparent, as 
shown in the mounted specimens. The deposit is full of their 
opercula, which have become separated from the shells, and in 
themselves are very pretty with their concentric markings, being, 
in fact, plates of growth in different stages of the creature’s 
existence deposited one over another. The mollusc is very common 
and very timid, retreating into its shell with the slightest touch. 
It floats under the water and deposits its eggs, ten to seventy 
in number, on stones or on aquatic plants. In the third family, 
Valvatidee, no specimen is found in my collection. In the second 
order, Pulmonobranchiata, there are a large number of specimens 
from the family Limneeide. In the first genus, Planorbis, Mr. 
Rimmer has named for me the small and really microscopical 
species, P. Wautileus. I think it is the gem of the collection when 
viewed under a low power, bearing a striking resemblance to the 
beautiful curves and ridges of the well known Nautili which has 
originated its specific name. Another species in this family which 
is in my collection is P. complanatus, a discoid shell of much 
larger size. Both species are shy and irritable, attaching themselves 
to aquatic plants and dropping from their attachments instantly if 
touched. In the third genus, Limnza, Mr. Rimmer has named 
for me L. feregra, a species which is very abundant in the collec- 
tion, both in its young and mature stages. This mollusc inhabits 
ponds and ditches, climbing the stems and leaves of plants above 
water-mark and fond of wandering. It is also very predatory, and 
has been known to attack and eat minnows, and even other 
mulluscs of its own species. In Mr. Rimmer’s book its prolific 
character is stated in the fact that a single creature has been known 
to deposit 1,300 eggs in one season, There is one other shell in 
the collection which Mr. Rimmer has also named for me, and this 
is the single specimen of land-shell, Pupa umbilicata, which 
I produce to you this evening. It belongs to the third family of 
terrestrial shells, termed Helicide, and the sixth genus of that 
family. It inhabits the crevices of walls or lives under stones and 
fallen leaves. The only remaining shells that have been discovered 
in the collection are those which I have already referred to as 
belonging to brackish water, Aydrobia ventrosa. They are 
pretty shells and were found on the outside of the bath and not in 
the mud bank, but I found them in very considerable quantities. 
The mud itself, after boiling with acids, has yielded a fair propor- 
tion of diatom valves :—Cocconeis placentula; Navicule ; Pinnu- 
laria viridis ; Cyclotella ; all of which are fresh-water species, but 
I also have found fragments of Coscinodiscus, which are only 
