1 UPA UMHiLicATA (i)i’:q).) Xot Uncommon under dead leaves 
ami at the roots of moss. 
Pupa makginata (Drap.) Ditto. 
\ KKrioo pygmjEa (Drap.) Sandjjit on tlie Ipswich road. 
„ EDENTULA (JJrap.) Tliorpe, and near Mangreen Hall. 
IhvLiA PERVER.SA (Liiuie.) Fourteen specimens from a wall at 
'I'horpe, benoatli ivy. 
(^LAUSiLiA RUGO.SA (Drap.) Common. 
„ LA.MiNATA (Moiitagu.) liitliiigliam wood, abun- 
dantly on the trunks of elder trees, and sevenil other woods 
sparingly. 
(.-ocfiucoPA LUiiRiuA (iMliller.) (’ommon at the roots of mos.s. 
Achatina acicula (Miiller.) At tlie roots of gms.s. 
CARYGU 1 U.M MINIMU.M (Miiller.) Abundant under dead leaves 
in woods. 
CYCLOSTO.MA ELEGAN’.s (Miiller.) ■\Vhitlinghain. 
Acme li.\eata (Drap.) Two s])ecimens from Caistor wood. 
VII. 
ON THE SPOXGEOUS OEIGIN OF FLINDS. 
By Frederic Kitton, V.P. 
Rooi 27th Fehruary, 1872. 
I HE origin of the nodules of silica so frequently .seen in the chalk 
has long puzzled the geological student as well as the casual 
observer, many besides myself have doubtless been told, that some 
of those nodules were petritied birds, (not stone curlews,) indeed 
the outline of some of them resemble the contour of a bird in no 
inconsiderable degree. The probable origin of Flints I shall have 
the pleiYsure of describing to you this evening, and in order to 
make the eviilences of this origin stronger, I shall trespass on your 
time and patience whilst I give a short description of that class of 
organic forms known as Sponges. 
Gt all tlie protozoic tonus the sponges are probably the only 
E 2 
