ADDENDA. 97 



Allied to Natica Montr euilensis, Heb. and Desl., from the Kelloway Rock of Montreul- 

 Bellay, which species, however, is less depressed and the aperture more lengthened. 



The ornamentation of the surface in our shell is partially preserved, and can only be 

 perceived by the aid of magnifying power. 



Geological Position and Locality. The Forest Marble of Laycock ; in the collection of 

 W. Walton, Esq. 



NATICA ARATA. Tab. XLV, fig. 2. 



Testa parva, crassa, inflata, spira exserta, anfractibus (4) convexis, ultimo, permagno, 

 transverse striato, suturis valde impressis, apertura ovata, umbilico nullo. 



Shell small, thick, inflated, spire produced, volutions (4) convex, the last volution very 

 large and globose, with delicate encircling striations, the sutures deeply impressed, the 

 aperture is ovate ; there is no umbilicus. 



Geological Position and Locality. The Great Oolite of Bussage ; collected ty E. 

 Witchell, Esq. 



NATICA (EUSPIRA) ALTA, Lye. Tab. XLV, figs. 22, 22 a. 



Testa parva, laevigata, subglobosa, spira elongata, apice acuto, anfractibus (4) con- 

 vexis, latis, suturis valde impressis, anfructu ultimo permagno, subgloboso, apertura ovata, 

 obliqua, subumbilicata. 



Shell small, smooth, spire elevated, its apex pointed, volutions (4) convex, moderately 

 wide, the sutures strongly marked, slightly constricted, the last volution very large, sub- 

 globose, the aperture ovate, oblique, the inner lip prominent, the base with an umbilica? 

 groove. The height of the aperture is slightly greater than that of the other portion of the 

 shell. Perhaps this is the young condition of a much larger species. 



Geological Position and Locality. The Forest Marble of Laycock ; in the collection 

 of W. Walton, Esq. 



NATICA INSIGNIS, Lye. Tab. XLV, fig. 21. 



Testa parva inflata, spira elevata, acuta, anfractibus (7) convexiusculis, angustis, 

 suturis dene impressis, anfractu ultimo permagno, subgloboso, apertura ovali, umbilico nullo. 



Shell small, inflated, spire much elevated, its apex acute, volutions (7) moderately con- 

 vex, narrow, the latter two volutions increasing rapidly, and becoming much inflated, the 

 last volution is very large, subglobose, the aperture rather depressed, ovate, with no distinct 

 umbilicus, or with a slight groove. 



13 



