26 



tion of its spiral band or angulation on the lower whorls of the spire, 

 and by the much more strongly marked constriction of the same whorls 

 above the angulation. In M. Boyld the spiral band is described as 

 being situated a " little above the suture, causing the lower part of 

 each whorl to project over the upper portion of the whorl next below,"* 

 while in M. constricta the spiral band, although situated below the 

 middle, in the later whorls of the spire, is removed from the suture 

 below by a distance equal to at least one-fourth the entire height of the 

 whorl. 



MURCHISONIA TUERITIFORMIS, Hall. 

 Plate 4, fig. 5. 



Murchisonia turriiiformis, Hall. Palaeont. N.Y., Vol. II., p. 347, pi. 61, figs. 6a & 6b 



The original description of this species is as follows: " Spire elon- 

 gated, turritiform, composed of numerous flattened volutions : surface 

 unknown ; columella small. This species is readily distinguished by 

 its flattened volutions, which, in the cast, present the marks of a carina 

 near or a little below the centre. One specimen preserves five volu- 

 tions, being imperfect at both extremities : the shell originally had 

 probably not less than fifteen volutions.'' " Position and locality. In 

 the limestone at Gait, Canada West." 



The two imperfect casts upon which this species was based were 

 obviously insufficient to enable its characters to be accurately defined. 

 Much more perfect specimens of a Murchisonia, which certainly corre- 

 spond better to the description and figures of M. turritiformis than to 

 those of any other species of the same genus from the Guelph Forma- 

 tion, have since been collected at Gait, Elora, Hespeler and Durham, by 

 Messrs. A. Murray, E. Bell, T. C. Weston, J). Boyle, and J. Townsend. 

 One of these specimens, in the Museum of the Survey, is labelled M. 

 turritiformis in the handwriting of Mr. B. Billings, while another and 

 more perfect one is represented by figure 5 of plate 4. In all of these 

 shells the whorls of the spire are encircled near but a little below their 

 middle by a narrow and not very prominent, spiral band or obtuse 

 angulation, which is scarcely strongly marked enough to leave its 

 impress upon the cast. Above the band the whorls are slightly con- 

 cave, and beneath it as slightly convex. On the outer half of the body- 

 whorl the band is placed a little above the middle, and the base is 

 rather strongly convex. The test seems to have been thin, and near 

 the mouth its surface markings consist of fine and rather crowded 



* Report upon the Pateontology of the Province of Ontario, 1875, p. 71. 



