119 
aperture. The aperture transversely oval, sub-elliptical ; the outer lip not reflected, and meet- 
ing the volution above nearly at right angles, but not prolonged further forward than the 
lower margin of the aperture. No umbilicus. Surface cancellated with numerous revolving 
and transverse thread-like striz, the former about seven and the latter three or four in the 
space of one line. Between the concentric striz are numerous finer striz, having the same 
direction, but so delicate that they can only be detected by the use of a high magnifying 
power. On the columellar side of the aperture the transverse strize radiate from a point, the 
revolving strize running nearly parallel with the inner lip, and the cancelli are nearly square, 
whereas elsewhere they are oblong. The transverse striz have a most peculiar and character- 
istic curvature ; springing from the suture above, they are directed obliquely backwards with 
a dorsal concavity ; they then make a great curve of which the convexity is directed dorsally, 
and which is situated on the lateral aspect of the whorl, and then finally they are again curved 
in the opposite direction, so that their convexities are directed towards the aperture. Whether 
the form of the outer lip conforms to this curvature of the concentric striz has not been 
determined. 
Height of specimen, twelve lines ; breadth, twenty lines. Height of aperture ten lines ; 
width of aperture, fourteen lines. 
This species, whether rightly referred to Strophostylus or not, appears to be distinguishable 
by its peculiar form and the characters of its surface-ornamentation. 
Locality and Formation.—Corniferous Limestone of Port Colborne. 
147. SrropHosTYLUS OBLIQUUS (Nicholson), 
(Plate II., Figs. 11, 11). 
Shell obliquely elliptical, its height being to its width nearly as one to three. Spire 
small, slightly elevated ; volutions three or four, rapidly increasing in diameter ; the body- 
whorl greatly expanded. The volutions of the spire are simply rounded and convex, but the 
body-whor] is obliquely flattened above, so that its upper surface joins the volution above, 
almost at an angle of 180.° Sutures obscurely canaliculated. Under surface slightly hol- 
lowed out; asmall umbilicus. Aperture obliquely ovate, slightly angulated above ; its height 
nearly double its width ; the outer lip thin, the columellar lip unknown. Surface cancellated 
with strong revolving strize, and much finer and more closely-set transverse striz. 
Height of specimen, about eight lines ; width, eighteen lines; beight of aperture, four- 
teen lines ; width of aperture, nine lines or less. 
This species is distinguished from all other species of Strophostylus, both by its surface- 
characters and by its very peculiar obliquely-elongated form. It would seem to be somewhat 
allied to S. transversus (Hall), but as the columella is not known, its reference to Strophostylus 
is rendered doubtful. 
Locality and Formation.—Corniferous Limestone, Port Colborne. 
Genus HOLOPEA (Hall). 
‘Shell conical, ventricose, more or less oblique or nearly direct; aperture round-oyate ; 
margin entire ; surface marked by simple fine curved strie, or cancellated”’ (Hall, Pal. New 
York, Vol. I., p. 169). ) 
The limits of the genus Holopea can hardly be rigidly defined as far as our present 
knowledge goes. In general form Holopea is closely similar to Cyclonema, and the character- 
istic surface-ornamentation of the latter is sometimes present in the former. An umbilicus 
appears to be usually present in /olopea, and is universally absent in Cyclonema, but it is 
sometimes wanting in the former genus also. From Strophostylus, the genus Holopea is dis- 
tinguished by its more elevated spire, its turbinate form, and its less ventricose body-whorl 
and less expanded aperture. 
The following species from the Corniferous Limestone of Ontario may be referred, at any 
ate provisionally, to the genus Holop ea. 
