GASTEROPODA. 145 



7. Natica otbeiformis. /. So 10. Tab. XVI, fig. 7, a — b. 



Naooa ciRMFOiiMis. J. Sow. Min. Conch, t. 479, fig. 1. 



— S. Wood. Catalogue 1842. 



— Morris. Catalogue of Brit. Fossils, p. 152, 1843. 



— Nyst. Coq. foss. de Belg. p. 444, pi. 39, fig. 1, 1844. 



N. Testa g/obosd, eras-set, Icevigatd ; anfractibus sex, convexis ; spird depressd ; aper- 

 turd semilunald ; labio inferne calloso ; umbilico lato, prof undo. 



Shell globose, thick, smooth; volutions convex, tumid; spire slightly elevated; 

 umbilicus wide and deep, with a broad sinus in the left lip, callous at the lower 

 part ; aperture semilunate. 



Longest diameter, 1-J inch. 



Locality. Cor. Crag, RamshokV 



I have not seen this species from the Red Crag ; and specimens of it from the 

 Coralline beds are generally in a decorticated state. Its distinguishing character is 

 the callosity at the lower part of a large umbilicus, the upper side of which has a 

 distinct ridge when the shell is well preserved, the left lip being, as it were, 

 separated in the middle by a deep and broad canal; unlike N. multipunctata, the 

 ridge is on the lower part of the umbilicus, and not in the middle; the volutions 

 expand, and are somewhat compressed above and below, forming a large and wide 

 umbilicus. 



8. Natica helicoides. Johnston. Tab. XVI, fig. 3, a — b. 



Natica heljcoidgs. Johnston. Hist, of the Berwickshire Nat. Hist. Club, 1834. 



— — Lyell. In Mag. Nat. Hist. 1839. 



— CANALiccLATA. Gould. Report on the Inv. of Massachusetts, p. 235, fig. 161, 1841. 



— helicoides. S 1 . Wood. Catalogue 1842. 



— — Morris. Catalogue of Brit. Fossils, p. 153, 1843. 



N. Testa ovaid, crassd, Icevigatd (?) ; spird elevatd ; anfractibus quatuor vel quinque 

 convexis; sufuris profundls ; aperturd ovaid; umbilico teeto. 



Shell ovate, thick, and smooth (?) ; spire elevated; volutions four or five, 

 convex, with a deep or canaliculated suture; aperture ovate, scarcely oblique, and 

 without an umbilicus. 



Axis, 1 inch nearly. 



Locality. Red Crag, Sutton. 



Mam. Crag, Bramerton and Br'dlington. 



Recent, North Seas and Coast of Massachusetts. 



This shell is rare in the Red Crag, though I believe it is not so in the Mamma- 

 liferous formation. It was given as an extinct species in the list of Mammaliferous 

 Crag Shells, published in the ' Mag. Nat. Hist. 1839,' the joint production of Mr. 

 Lyell, Mr. G. Sowerby and myself, as we were not then aware of its existence as a 

 recent shell. We have since been able to compare the recent and fossil shells, and 



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