ADDENDA. 101 
Shell small, inflated ; spire elevated; volutions (4) very convex, their posterior portions 
nearly horizontal, their anterior portions convex, with the sutures deeply impressed ; the 
last volution very Jarge and ovate; the aperture oval, no umbilical depression ; the surface, 
with lines encircling and perpendicular, very densely and irregularly arranged, having 
sometimes au imperfectly punctated aspect. 
It is allied to Zurbo gibbosus, D’Orb., but the latter is shorter and more inflated. 
Geological Position and Locality. The Forest Marble of Farleigh; in the collection 
of W. Walton, Esq. 
Monoponta comma, Lyc. Tab. XLV, figs. 24, 24a. 
Testa ovato-discoidea, anfractibus (4), elevatis, subplanis, suturis distinetis, anfractu 
ultimo magno, apertura elliptica, umbilico parvo, dente basili magno obtuso ; superficre strirs 
concentricis tenuissimis, regularibus. 
Shell ovate, discoidal ; spire elevated ; volutions (4) rather flattened, apex obtuse ; the 
sutures distinct ; the last volution large, rather depressed, aperture elliptical ; umbilicus 
small; basal tooth large, obtuse ; the surface has very delicate, closely arranged, regular 
encircling striations. 
The general figure nearly approaches to Monodonta (Crossostoma) heliciforme, but the 
latter shell is without ornamentation, and has a smaller and more depressed basal tooth 
and sulcus. 
Geological Position and Locality. The Forest Marble of Farleigh ; in the collection 
of W. Walton, Esq. 
Monoponta Wattont, Lyc. ‘Tab. XLV, figs. 31, 31a, 6. 
Testa crassa, ovoidea, tenuissime concentrice striata, spira brevi depressa, suturis 
distinctis, anfractibus (5) angustis, subconvenis, anfractu ultimo permagno ; basi obliquo 
subumbilicato, dente et sulco magno obtuso ; apertura ovata. 
Shell thick, ovoidal, delicately concentrically striated ; spire short, depressed; volu- 
tions (5) narrow, slightly convex, their sutures distinct, the last volution very large, base 
oblique, and slightly umbilicated ; the basal tooth and sulcus prominent ; aperture ovate, 
outer lip thick. 
A pretty little delicately ornamented species, of twelve examples the smallest is 
scarcely larger than the head of a pin, and has a distinct umbilicus ; the largest has a 
diameter of four lines. 
Geological Position and Locality. The Forest Marble of Farleigh; in the cabinet of 
W. Walton, Esq. 
