257 



Gasteeopoda. 



Pleurotomaria (or EuoMPHALOPTERUs) sp. indet. 



Upper rapid : five badly preserved casts of the interior of the shell of a 

 ■widely umbilicated species of Pleurotomaria or Euomphalopterus, with a 

 very low, obtuse spire. These specimens are very similar in shape to 

 casts of Pleurotomaria Valeria, Billings, which is an Euomphalopterus, 

 but the outer whorl of each is not so distinctly keeled at the periphery. 



Euomphalopterus, sp. indet. 



Foot of portage road ; a specimen with the upper half of the shell com- 

 pletely worn away, the basal half, which is all that is left, being narrowly 

 umbilicated and showing part of a peripheral alation. 



Megalomphala eobusta, Whiteaves. 



Plate 28, figs. 9 and 9 o ; and pi 29, fig. 1. 



Megalomphala robusta, Whiteaves 1904. Geol. Surv. Canada, Ann. Rep., vol. 



XIV, pt. F, p. 48. 



" Shell large for the genus, strongly convex but deeply and rather widely 

 umbilicated on both sides, the umbilicus occupying about one half of the 

 entire diameter though its margin is not very distinctly defined. Whorls 

 at least three and perhaps more, increasing very rapidly in size and 

 laterally expanding, coiled closely on the same plane and everywhere in 

 close contact, but with little or scarcely any overlapping ; their periphery 

 encircled by a continuous slit-band ; exposed portions of the inner ones 

 truncated almost vertically but somewhat obliquely on each side. Outer 

 whorl rounded on the periphery in some specimens, faintly and obtusely 

 subangular in others, distinctly subangular round the umbilical margin on 

 both sides, the umbilical wall being steep but somewhat oblique. Slit- 

 band narrow, in half grown specimens moderately elevated and bounded 

 on each side of its summit by a spiral raised line, but this minute double 

 keel becomes obsolete on the outer half of the last volution, in adult 

 shells. Outline of transverse section near the aperture subreniform and 

 much wider than high in some specimens but somewhat triangular and 

 nearly or quite as high as wide in others ; outer lip not preserved in any 

 of the specimens collected, but apparently not abruptly expanded ; aper- 

 tural slit unknown. 



" Surface of most of the specimens collected marked only with curved, 

 transverse strise of growth, but in one specimen the markings consist of 

 small narrow, thin transverse ridges, with flat spaces between them. 



