CANADIAN FOSSILS. 23 



M. VENTRICOSA, Hall. 



Plate V. Figures 2, 3. 



M. turrita, anfractibus rotundatis ventricosis Icevigatis, superne subangula- 

 tis, et cingulo lato marginato prope suturam posito ; ore rotundato. 



Synonym. — M. ventricosa, Hall, Palaeontology of New York, vol. i., 

 plate 10, figure 3. 



The position of the band easily distinguishes this fine species from 

 the M. bellicincta, Hall, with which its size and general shape would 

 lead us at first sight to identify it. It has the same proportions of 

 spire, and convexity of the whorls, and the pillar-lip is straight, as 

 described by Hall, though his figures do not clearly shew this 

 character.* But the band, instead of being nearly central and rather 

 narrow, is broad, flat, and placed so high up as to be less than its 

 own breadth from the suture; while the lower margin forms the 

 prominent angle seen above the middle of the whorl. The lines of 

 growth curve back much in the way figured in the M. bellicincta, 

 and far less sharply than in M. gracilis, tending back to the broad 

 band, in which they are much curved, and then forward again, leav- 

 ing an open angle of about 100°. 



Any comparison with other allied species seems unnecessary, as, 

 except M. bellicincta, there is no American species likely to be 

 confounded with it. Plcurotomaria injlata, McCoy, Silurian fossils, 

 Ireland, is a kindred species, but quite distinct. 



It is found in tolerable plenty associated in the same slabs with 

 the M. bicincta, Orthoceras arcuoliratum, Cyrtoceras Billingsii, and 

 Strophomcna planumbona, at Allumette Islands. Hall's specimens 

 were found at the junction of the Birdseye and Trenton limestones 

 in the Mohawk valley. 



Cyclonema, Teochonema, Eunema. 



Decade I. Plate VI. 



Cyclonema, Hall. 



Cyclonema, Hall. Mollusca Gasteropoda. Family Litorinidae. 

 Turbinate, thin, of few ventricose whorls, with concentric striae 



* It is with some doubt this is referred to Hall's very imperfect figured specimen. 

 His description however agrees accurately, and it is useless to multiply names. 



