550 H. A. NICHOLSON ON THE GASTEEOPODA OF 



Pletjeotomaeia solaeioides, Hall. Plate XXVI. fig. 15. 



P. solarioides, Hall, Pal. N. Y. vol. ii. p. 348, plate lxxxiv. 

 figs. 4 a, b. 



Shell depressed, of four or five volutions, which are convex ex- 

 ternally. Umbilicus very large, exposing the whorls to the apex 

 (in the cast). The base is nearly circular, and has a diameter of ten 

 lines in an average individual. The whorls are flattened from above 

 downwards ; and the body- whorl is not expanded. Surface and aper- 

 ture unknown. 



I do not feel at all sure as to the true position of the specimens 

 which I have referred here. They occur wholly in the condition of 

 casts ; and though I have no doubt as to their identity with the ex- 

 amples described by Hall under the above name, their generic affini- 

 ties seem very doubtful. They exhibit no evidence of a carina, and 

 are just as likely to belong to Straparollus as to Pleurotomaria. 



Formation and Locality. Guelph Limestones ; Elora and Hespeler, 

 Ontario. 



Pleueotomaeia, sp. Plate XXVI. figs. 13, 14. 



Shell conical, with an elevated spire. Whorls four, narrowly 

 rounded below, but nearly flat for their upper two thirds (in the 

 cast). Suture deep. Body-whorl expanded moderately towards the 

 aperture. Base somewhat flattened, showing in the cast a small 

 umbilicus. Surface unknown. Aperture apparently rounded. 



Length of a large specimen seven lines, width of the base six 

 lines. In a small specimen, the length is five lines, and the width 

 of the base is four and a half lines. 



In some respects, this form resembles Pleurotomaria elora, and 

 P. galtensis, Billings, though very clearly distinct. Indeed it may 

 be doubted whether it belongs to Pleurotomaria or whether it may 

 not rather be referable to Holopea. I cannot identify it with any 

 previously recorded form ; but my specimens are all in the condition 

 of casts, and I prefer to leave its specific position an open question. 



Formation and Locality. Guelph Limestones ; Elora, Ontario. 



Holopea (?) occidentalis, Nicholson. "Woodcut, p. 551. 



Shell conical, with a small but elevated spire. Whorls five, convex, 

 with the greatest convexity in the upper fourth. Body-whorl ex- 

 tremely large, occupying nearly three fourths of the length of the 

 shell. The body-whorl is moderately expanded towards the aperture, 

 at which point it is almost free. Aperture circular. In the cast 

 there is a large umbilicus. 



The length of the shell is twenty-one lines ; the width of the base 

 (including the aperture) is nineteen lines ; the height of the body- 

 whorl is fifteen lines ; the height and width of the aperture are both 

 nearly nine lines ; the width of the umbilicus is four lines ; and the 

 height of the spire is about six lines. Surface- characters unknown. 



It is impossible to feel certain whether this form is rightly referable 

 to Holopea or not, though its general form would lead us to place it 



