Vol. 58.] REFERRED T0 MURCHISONIA AND PLEUROTOMARIA. 327 
CyrrosTRoPHA opscuRA (Portl.). (Pl. VIII, figs. 2, 2a, & 3.) 
Loxonema obscura, J. E. Portlock, 1843, ‘Geol. Rep. Londonderry’ p. 415 & 
pl. xxxi, fig. 3; (?) H. G. Bronn, 1848, ‘Index Paleont.’ pt. 1, p. 670. 
Murchisonia obscura, J. Morris, 1854, ‘ Catal. Brit. Foss.’ 2nd ed. p. 259; J. Sowerby, 
1867, ‘Siluria’ 4th ed. p. 197, Foss. 40, fig. 3; J. J. Bigsby, 1868, ‘ Thes. Silur.’ 
p. 158; (2) J. Armstrong, J. Young, & D. Robertson, 1876, ‘Catal. West. Scot. Foss.’ 
p. 19; pars, A. C. Ramsay, 1881, Mem. Geol. Surv. vol. iti, ‘Geol. N. Wales’ 2nd 
ed. p. 414; R. Etheridge, 1888, ‘Foss. Brit. Is.’ vol. 1 (Paleozoic) p. 113; (?) J. 
Horne & B.N. Peach, 1899, Mem. Geol. Surv. ‘Silur. Rocks of Britain’ vol. 1, pp. 682 
& 695; (2) B. N. Peach, J. Horne, & A. Macconochie, 1901, in ‘ Fauna, Flora, & Geol. 
of Clyde Area’ publ. by Local Comm. for Meeting of Brit. Assoc. Glasgow, p. 438. 
Diagnosis.—Shell elongated, turreted, composed of more than 
seven whorls. Whorls increasing at a moderate rate, convex, more 
or less smooth. Band situated near the middle of the body-whorl 
aud below the middle of the whorls of the spire, slightly depressed, 
bounded by an indistinct ridge on each side. Lines of growth 
sloping back to the band above, and forward again below. Aperture 
imperfectly known, sub-ovoid. Base produced. No umbilicus. 
Remarks.—The only known examples of this species are very 
imperfect, being fragmentary, compressed, and much weathered. It 
bears more resemblance to Cyrtostropha than to true Murchisona, 
especially as on a wax-impression (taken from an external mould) 
there appear to be indications of the groove above the band bounded 
by a thread, so universal in this subgenus. It was originally 
regarded as Loxonema by Portlock, but the possession of a band 
distinguishes it from the members of that genus. 
Localities and Horizon.—In the Museum of Practical Geology, 
Jermyn Street, are two specimens which are little better than internal 
moulds, and the external impression of one of these, from rocks of 
Bala age at Desertcreight (Tyrone). One of these (Pl. VIII, fig. 2) is 
Portlock’s type; it has the apex broken, the seven remaining whorls 
measuring 27 millimetres in length and 13 mm. in width; as the 
specimen is flattened by pressure, the width appears greater than 
it must have been originally. Another fragment from Tyrone, 
consisting of about two whorls, is referred to this species, but I am 
uncertain as to its identity; it is embedded in the matrix, and the 
band appears to be higher than in the type. In the Harkness 
Collection, in the Carlisle Museum, are two examples: one from the 
Chair of Kildare, and the other from Pomeroy, referred to this 
species, but they are too badly preserved to admit of precise deter- 
mination. I feel very doubtful whether the specimens in the Scottish 
lists which are called Murchisenia obscura are really referable to this 
species; those in Mrs. Gray’s collection are certainly not identical. 
CyRTostROPHA RoBUSTA, sp. noy. (Pl. VIII, fig. i) 
Diagnosis.—Shell elongated, conical, composed of more than 
ten whorls. Whorls increasing gradually, convex, slightly flattened 
above. Band situated on the widest part of the whorl, rather below 
the middle, almost level with the surface, bounded on each side by 
a strong raised thread. Lines of growth sloping back to it above 
and advancing with greater obliquity below, not seen on the band 
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