100 



MOLLUSCA. 



BCLLA. 



Subdiscoidal ; spire depressed, with four flattened volutions, 

 with an indistinct carina at the base of each ; body flat above, 

 and carinated, convex beneath ; callus, narrow, and rather ele- 

 vated, and not so distinct as in the former species; surface with 

 obscure strix. 



Lias, Lyme Regis, Dorsetshire. 



3. CocHLicARiNA coMPRESSA. — The CoDipressed Cochli- 

 carina, pi. XLVII. fig. 7, 8. 



Ilelicina cumpressa. Sowerby, I. p. 33, pi. 10, three middle 

 figures. Fleming, p. 258. 



Subglobose, smooth, thick, and strong ; spire slightly depres- 

 sed ; superior portion of the body, and base of the volutions of 

 the spire, carinated; base convex; callus broad; aperture some- 

 what angular above. 



In Lias Limestone, Gloucestershire. 



4. CocHLlCAUiNA POLlTA. — The Polishcd Cochlicarina, pi. 

 XLVIL fig. 5, 6. 



Helicina polita. Sowerby, III. p. 153, pi. 285. Fleming, 

 p. 258. 



Subrotund, smooth, polished ; spire subconic, consisting of 

 five volutions, subdepressed above, with a carina at their base, 

 which continues along the superior portion of the body, and 

 terminates in the outer lip ; body separated from the spire by 

 an impressed fillet, and finely rounded below, with a thin callus 

 expanded half over the base ; aperture subquadrangular ; upper 

 parts with perversely arcuated lines of growth, which indicate a 

 sinus in the right lip. 



In Marly Sandstone of the Lower Oolitic series at Cropredy. 



Genus LV'II HELIX Linnaus. 



Shell orbicular, thin, subglobose; body very large; 

 spire short, and small in proportion to the body; aperture 

 oblique; outer lipMeflected, and interrupted by the bulg- 

 ing of the body ; columella confluent with the outer lip, 

 and situate on the lower portion of the axis ; destitute ot 

 an operculum. 



1. Helix Gentii— Gent's Helix, pi. XLVII. fig. 9, 10. 

 UelixGenlii. Sowerby, II. p. 101, pi. 145. Fleming, p. 264. 

 Subglobose, smooth; body large; spire small, consisting of 



three depressed volutions, the apex obtuse; superior portion of 

 the body, and base of the volutions, provided with a spiral, 

 narrow, hollow band, or sulcus; aperture elliptical, ample, 

 much expanded ; whole surface furnished with obscure, arcu- 

 ated lines of growth, except in the sulcus, where they are more 

 conspicuous. 



Greensand near Devizes. 



2. Helix clobosa. — The Globular Helix, pi. XLVII. fig. 

 33, 34. 



Ilclix globosus. Sowerby, II. p. 1.57, pi. 170. Fleming, p. 264. 



Globular, slightly longer than broad; body very large; spire 

 rather short, obtuse, consisting of three rather broad, slightly 

 tnmid, and gradually increasing volutions, with obscure, irregu- 

 lar, spiral stria-, and crossed by lines of growth ; aperture scnii- 

 lunatc ; outer lip slightly reflected ; umbilicus concealed by the 

 expanded glazing on the columellar lip. 



Young thells arc ■omcwhat depressed, provided with an umbilicus. 



Crag, Fresh Water formation, Isle of Wight. 



ORDER IV.-GASTEROPODA. 



Animals with the body straight, never spiral, nor 

 totally enveloped in their shell; the foot, or disc, situated 

 under the belly, united to the body nearly its whole 

 length, and serving as an organ of locomotion. 



Grand-Division L— PNEUMOBRANCHI/E. 



Branchiae in the form of a vascular net, or the wall of 

 a particular cavity, opening by a hole, which the animal 

 contracts or dilates at pleasure. They respire air. 



FAMILY I.— BULLACEA. 



Shells greatly distended, and without any apparent 

 columella. 



Genus I. — BULLA — Linnmis. 



Shell convolute, oval, w'ith a depression above instead 

 of a spire; aperture longitudinal, as long, or longer than 

 the convolutions, straitened above, and expanded beneath, 

 where it is effuse; outer lip thin; columellar lip generally 

 reflected, with a coating of shelly matter. 



1. Bulla convoluta. — The Convoluted Bulla, pi. XLVII. 

 fig. 11, 12. 



Bulla convoluta. Brocchi, p. 277, pi- 1, fig. 7. Sowerby, 

 V. p. 95, pi. 464, fig. 1. Fleming, p. 295. 



Cylindrical, smooth ; aperture narrow, linear, widened near 

 the base ; vertex obtuse, subtruncated, perforated, exposing a 

 deep umbilicus. 



In the Crag at Ipswich. 



2. Bulla elliptica The Elliptical Bulla, pi. XLVII. 



fig. 13, 14. 



Bulla elliptica. Sowerby, V. p. 96, pi. 464, fig. 6. Fle- 

 ming, p. 295. 



Regularly elliptical, elongated, rounded at both extremities j 

 vertex deeply perforated; aperture linear, wider below than 

 above ; surface with fine, regular, transverse stria;, somewhat 

 wider near the base. Three lines long. 



London Clay, Barton Clifl". 



3. Bulla elongata The Elongated Bulla, pi. XLVII. 



fig. 19. 



Bulla elongata. riullips, I. p. 1U2, pi. 4, fig. 7. 



Elongated, smooth, narrow, and umbilicatcd above, wide 

 beneath; outer lip thin, and somewhat hollow in the centre; 

 aperture contracted above, rounded, and wide beneath. 



Coralline Oolite, in the lower beds at Seaniar, Malton, and 

 Scarborough. 



4. Bulla filosa.— The Thready Bulla, pi. XLVII. fig. 20. 

 BulUJilosa. Sowerby, V. p. 97, pi. 464, fig. 4. Fleming, 



p. 295. 



ICIIiptical; aperture narrow above, wide, and rounded beneath; 

 outer lip considerably expanded; surface covered with numerous, 

 regular, transverse stria;. 



Distinguished from the preceding by its expanded lip and oumeroui 

 •trix. 



