560 MISS JANE DONALD ON THE GENEEA [Nov. I906, 



concave above, and flat below. Sinual band situated immediately 

 below tbe angle, which is above the middle of the body-whorl 

 and below the middle of the whorls of the spire ; it is broad, and 

 composed of three strong raised threads. The lines of growth 

 curve obliquely back to it above and obliquely forward below, not 

 being observed on the band itself. The ornamentation consists of 

 a strong thread a short distance below the band, and a very fine 

 thread immediately below the upper suture. Umbilicus closed. Base 

 convex. Aperture sub-ovoid, longer than wide; columella nearly 

 straight. 



Eemarks and Resemblances. — There are about twenty- 

 seven specimens of this species in Mrs. Gray's collection. It is 

 hardly a characteristic Lophospira, but seems more like species of 

 this genus than those of Goniostroplia, (Ehlert, to some species of 

 which it also bears a resemblance, more especially to such a form as 

 Goniostropha Marsi, (Ehl., 1 from the Devonian. Nevertheless, I 

 consider it advisable to place it in Lophospira, until the exact 

 character of the sinual band is known. In the form of the band 

 and ornamentation it is very like L. instabilis, which also occurs 

 in beds of the same age, but it is more elongated, having more 

 numerous whorls ; the umbilicus is closed, and the lower keel is 

 nearer the band. Among American species it comes nearest to 

 Murchisonia perangulata, Hall, 2 from the Trenton Formation, but 

 the band of that species is said to be double, whereas in this the band 

 is formed of three almost equally-strong keels, the lower thread 

 ornamenting the surface is nearer the band, and the upper one is 

 very fine instead of being a distinct keel. 



Dimensions. — The biggest specimen has about nine whorls; it 

 is from Thraive Glen, and measures 11 millimetres in length and 

 about 6 mm. in width. It is not so well-preserved as a smaller 

 example from Shallock Mill figured in PI. XLIII, fig. 7, which 

 consists of eight whorls in a length of 9 mm., whose greatest width 

 = 3-5 mm. Another shell, from Drummuck, the body-whorl of 

 which is figured in PI. XLIII, fig. 7 a, on account of its snowing the 

 lines of growth, consists of seven whorls in a length of 5 m 5 mm., and 

 its width = 3*75 mm. 



Locality and Horizon. — Mrs. Gray's collection contains 

 numerous specimens from the Upper Bala of Thraive Glen and of 

 Drummuck, and from the Middle Bala of Shallock Mill (all in 

 Ayrshire). 



LOPHOSPLRA INSTABILIS, Sp. nOV. (PI. XLIII, figS. 8-10.) 



Diagnosis. — Shell turbinate, composed of about six whorls. 

 Whorls angular above the middle of the body-whorl and near the 

 middle of the earlier whorls, flattish above and nearly vertical 

 below the angle, smooth with the exception of a keel a short 

 distance below the band and a fine thread immediately below the 



1 Bull. Soc. litud, Sci. Angers, 1887 (sep. cop.) p. 17 & pi. viii, fig. 1. 



2 Pal. New York, vol. i (1847) p. 179 & pi. xxxviii, figs. 7a-7b, non pi. x, fig. 4. 



