259 



six or seven, rounded, ventricose ; aperture widely subovate, not far from 

 circular, lip thin and simple. 



" Surface marked with numerous and rather close-set small spiral ridges, 

 that are crossed by still more numerous, more close-set and minute, trans- 

 verse raised ■ lines. On the last whorl but one there are about eight of 

 these spiral ridges, and on the last or outer one there are not less than 

 twelve and probably as many as fifteen. 



" Portage road at falls : two specimens. The larger of these was pro- 

 bably about forty -five millimetres high or long, when perfect, and its 

 maximum width is thirty-five mm.'' 



Gyronema Dovvlingii, Whiteaves. 

 Plate 29, fig. 3. 



Gyronema Dowlingii, Whiteaves 1904. Geol. Surv. Canada, Ann. Rep., vol. XIV, 



pt. F, p. 50. 



" Shell turbinate, higher or longer than wide, spire elevated, volutions 

 rounded and ventricose ; umbilicus almost or quite closed. Lower whorls 

 of the spire marked with three rather distinct, acute and prominent spiral 

 keels. Outer whorl encircled by four comparatively large spiral keels and 

 by a few much smaller spiral ridges, or minute raised lines. Between the 

 second and third spiral keels there are three close set, low and rounded, 

 minute spiral raised lines, and there are indications of a few small spiral 

 ridges in the umbilical region, below the lowest of the four large spiral 

 keels. 



" Portage road at falls : one imperfect specimen with the apical whorls 

 broken oif, but with the test preserved on the last two whorls of the spire 

 and on part of the outer whorl. 



" A rather smaller species than the preceding and with very difierent 

 sculpture. It is somewhat similar in shape to the Cydonema sulcatum of 

 Hall, from the Guelph formation of Ontario (which is probably a Gyro- 

 nema rather than a Polytropis). But the whorls of G. Dowlingii are not 

 shouldered above, its suture is not channelled, and its outer volution is 

 encircled by only four large spiral keels. G. Dowlingii is still more closely 

 allied to, but apparently quite distinct from, the Cydonema carinatum. of 

 Sowerby, as figured by Lindstrom in his monograph of the Silurian 

 Gastropoda and Pteropodaof Gotland, which Ulrich says is a Gyronema.'' 



Gyronema brevispira, Whiteaves. 

 Plate 29, fig. 4. 



Gyronema brevinpira, Whiteaves 1904. Geol. Surv. Canada, Ann. Rep., vol. 



XIV, pt. F, p. 51. 



" Shell rather small, turbinate conical and wider than high ; spire 



shorter than the outer volution. Whorls four or five, those of the spire 



2 



