548 H. A. NICHOLSON ON THE GASTEEOPODA OF 



deep suture. The outer edge of the body-whorl is narrowly rounded ; 

 but there are no distinct indications of a carina on this or on any 

 other of the volutions. Surface covered with fine lamellose striae, 

 which curve obliquely backwards from the suture to the lower edge 

 of the whorl. Length of the shell fourteen lines, width at the base 

 one inch. 



I should be inclined to doubt if this shell can be with any certainty 

 referred to Murchisonia ; but there can be no question as to its specific 

 distinctness. It has not only been recognized by Mr. Billings and 

 myself in the Guelph formation of Canada, but has been detected by 

 Hall in strata of the same age at Racine, Wisconsin (Twentieth 

 Report on the State Cabinet, p. 345). 



Formation and Locality. Guelph Limestones ; Elora, Ontario. 



Mtjkchisonia, sp. 



Shell conical, turreted, with a !Long spire. Whorls robust, rapidly 

 expanding, flat, the lower portion of each projecting beyond the upper 

 part of the whorl immediately below. There are obscure indications 

 of a band placed a little above the suture. Length of an imperfect 

 specimen two inches, width of the base fourteen lines. 



This form somewhat resembles M. Boylei in its general characters, 

 but is altogether much larger. The materials in my hands, however, 

 are not sufficient to permit of its satisfactory determination. 



Formation and Locality. Guelph Limestones ; Elora, Ontario. 



Cyclonema(?) elevata, Hall. Plate XXYI. figs. 16, 16 a. 



C. ? elevata, Hall, Twentieth Eeport on the State Cabinet, p. 342, 

 plate xv. fig. 4. 



Shell conical, with an elevated spire. Apical angle from 35° to 

 40°. Whorls five in number, convex, with a deep suture, gradually 

 enlarging to the aperture. Body-whorl not ventricose. Aperture 

 broadly ovate. Surface unknown. 



The best-preserved specimen in my possession has a height of 

 thirteen lines, the width of the base being ten lines. The height 

 of the aperture is six lines, the width of the same being five 

 lines. 



The specimens in my collection, though in all respects slightly 

 larger, so closely resemble the shell figured and described by Hall 

 under the name of Gyclonema ? elevata, that I do not feel justified in 

 separating them. One of my examples, however, exhibits distinct 

 indications of an obscure and shallow band about the centre of the 

 body-whorl, which is not the case in the specimens described by 

 Hall. The surface is stated by Hall to possess evidence of revolving 

 striae ; but I cannot bring forward any evidence on this head. My 

 specimens are all in the condition of casts, and exhibit a distinct but 

 small umbilicus. Upon the whole, I should be disposed to think that 

 the present form is probably referable to Holopea, presenting con- 

 siderable affinities with H. guelphensis, Billings. 



Formation and Locality. Guelph Limestones ; Elora, Ontario. 



