1847.] LYCETT ON THE OOLITE OF MINCHINHAMPTON. 181 
the ventral valve. In casts of old specimens of 7. reticularis the 
muscular impressions are seen to be analogous to those of the Ame- 
rican shell, but from a difference in the proportions of the various 
parts, our shell does not present the strong resemblance to the base 
of a horse’s hoof to which the 7’. unguiformis owes its celebrity and 
name. 
(16) Porcenu1a ornatas, Conrad sp.—Shell consisting of two 
or three whorls wholly exposed and increasing very rapidly in size ; 
whorls sharply carinated, ornamented on each side with a row of 12 
or 15 tubercles, which expand laterally into short ribs, occupying 
about half the width of the shell; back crossed by elevated rows of 
minute tubercles arranged in straight lines nearly at right angles to 
the keel: opening irregularly quadrangular. 
Found in the Hudson’s River group on the Salmon River, and in 
the blue limestone of Ohio at Cincinnati. 
I have no doubt that this is the Cyrtolites ornatus of Conrad and 
Vanuxem, although the specimens I have seen do not show the whorls 
detached in the manner represented in Mr. Vanuxem’s figure. The 
species is so nearly related to Porcellia Puzo of Léveillé, and P. 
armata of De Verneuil, that I could not hesitate to place it in the 
same genus, without having seen its true generic characters. 
A shell found in the Lower Silurian beds of North Wales near 
Bettws-y-Coed cannot be distinguished from the American species, 
although the specimen is hardly perfect enough to give a certain 
identification. The Hwomphalus Corndensis, Sowerby, Sil. Syst. t. 22. 
f. 16, may perhaps be also related to the genus Porcellia, and has 
some resemblance to this species. 
DECEMBER 15, 1847. 
John North, Esg., and Thomas F. Gibson, Esq., were elected 
Fellows of the Society. 
The following communications were then read :— 
1. On the Mineral Character and Fossil Conchology of the Great 
Oolite, as it occurs in the neighbourhood of MincHINHAMPTON. 
By Joun Lycert, of Minchinhampton. 
My principal design in this paper is to exhibit the organic remains 
of a district small in area, but peculiarly rich in fossil testacea. 
These likewise occur in a better state of preservation than is common 
in rocks of a similar geological character, the external ligaments 
of the bivalves, and coloured markings of the univalves, being not 
unfrequently visible. Of the remains of reptiles, fishes, crustacea, 
insects and plants of the oolitic period, the slates of Stonesfield have 
afforded good illustrations ; but the shells are comparatively few as 
to species. 
Mr. Lonsdale’s list from the vicinity of Bath, at the south-western 
extremity of the formation, is equally scanty. A few species may be 
found in the ‘ Mineral Conchology of Great Britain ;’ and recently 
