MURCHISONIA. 
315 
Though they themselves show some amount of variability they present a very 
close general resemblance to each other ; especially in the very narrow median 
sinus-band, the two ridges above it and the two or three below it, the sharp 
lamellar growth-strise, the fine indistinct tuberculation, the elongate mouth, and 
the general contour of the spire. Specimens of M. kirbinata may certainly be 
found which agree with them in one or two of these particulars, but in every case 
they are very distinguishable in others. The number and shape of the spiral 
ridges, both above and below the sinus-band, are especially distinctive. In none 
of the specimens of M. tnrhinata is there more than one ridge above it. In one of 
the present specimens it is true that the lower of the two ridges is much smaller 
than in the other, but even in this case it is constant and well defined. I therefore 
think that there is suflficient grounds for regarding it as a distinct species, 
although, if passage forms were found, this opinion might have to be modified. 
3. MURCHISONlA TBEPOMENA, n. sp. PI. XXX, figs. 16, 16 a. 
1841. Mtjkchisonia teicinota, Phillips (not Miinster). Pal. Foss., p. 139, 
pi. Ix, fig. 190 * 
1842. — — d' Arch, and deVern. Geol. Trans., ser. 2, vol. vi, 
pt. 2, p. 358, pi. xxxii, figs. 13, 13 a. 
1852. Pletteotomaria trilineata, Sandherger (not Qoldfuss). Verst. Eheiu. 
Nassau, p. 202, pi. xxiv, figs. 16, 
16 a. 
1854. MiTBCHisoisriA teicinota, Morris. Catal. Brit. Foss., p. 259. 
1888. — — Etheridge. Foss. Brit., vol. i, Pal., p. 164. 
Description. — Shell very elongate, subturrited, regular. Apex sharp. Spire 
very elongate and subulate, of twelve or fourteen, narrow, convex, very slowly 
increasing whorls. Suture deep, acute, facing upwards. Whorls more convex 
below than above, bearing at about two thirds the way down a narrow, concave 
sinus-band, bounded by two sharpish ridges. Surface above and below the sinus- 
band marked with two or three indistinct spiral ridges, of which the two most 
prominent are sutural and finely beaded ; the whole crossed by fine distant growth- 
striaB trending backwards to, and forwards from, the sinus-band. Mouth small, 
wide, subquadrate. Inner lip short, straight. Outer lip notched at the extremity 
of the sinus-band. 
Size. — Height, 32 mm.; width, 11 mm. 
Locality. — Wolborough. There are seven specimens in the Godwin-Austen 
Collection in the Museum of Practical Geology, four in Mr. Vicary's Collection, 
one in the British Museum, and two in the Woodwardian Museum. 
Bemarlcs. — One of the specimens in the Godwin- Austen Collection appears to 
41 
