186 



Width on the hinge Hne 6 or 7 lines. The area of the ventral valve 

 seems to be less than a hne in height. All the specimens are imbedded in 

 stone so that the area and foramen cannot be seen. 



This species resembles 0. Maria, (ante, p. 137, fig. 114,) but is not so 

 convex. 



Locality and Formation. — Point L^vis ; limestone No. 2, Quebec. 



Collectors. — Sir W. E. Logan, and T. Devine, Esq. 



Clisospira. (N. gen.) 



Generic Characters. — Aperture widely expanded all round in a plane 

 which is at a right angle (or nearly so) to the longitudinal axis of the spire, 

 the latter conical. The cavity occupied by the animal appears to be, at 

 least in the lower part, not spirally coiled, as in the ordinary gasteropods, 

 but straight and central, with the lip spread out all round, trumpet-like. 

 There is some evidence that towards the apex of the spire, it is spirally 

 coiled, but neither of the two specimens collected has this part preserved. 

 The suture is distinct in the spire, but seems to become obsolete on 

 approaching the lip. 



The specimens are so imperfect, that the affinities of this curious fossil 

 are not very apparent. Even the shell has a different aspect from that of 

 any gasteropod I have seen in the Lower Silurian rocks, being nearly black 

 with a horny texture. 



Clisospira curiosa. (N. sp.) 

 6 



Fig. 167. 



Fig. 161.— Clisospira curiosa. a, side view ; b, view of the specimen, loolting down 

 upon it from above. 



Description.— K-^txima trumpet-like, expanded to a width of about one 

 inch; spire central, or nearly so, sinistrally coiled, about five lines in 

 diameter at the height of six lines, about seven lines at the base, or Avhere 

 it passes into the wide hp. The whorls are depressed convex, and the 



