82 



MOLLUSCA. 



SCALAIIIA. 



fig. 1, 2. Helix catillus, Martin, Petrificata Derbiensia. Par- 

 kinson, Org. Rem. III. pi. 6, fig. 1 and 3. Skenea catellus, 

 Fleming, Brit. An. p. 31 J. 



Shell depresseil, consisting of four or five almost entirely 

 exposed volutions, with a prominent central carina, or ridge, 

 both above and below, and one side deeply unibilicate, in the 

 form of a hollow cone; aperture subtriangular, taking the sharp 

 form of both the carina?, the sides next the body being longest. 



DistingtiisUcd from E. pentangulatus, by the keel on its inferior sur- 

 face. 



Found in the Carboniferous and Mountain Limestone. 



G. E. DISCOBS. — The Discordant Euomphalus, pi. XLII. 

 fig. 32, 33. 



Euomphalus discors. Sowerby, Min. Conch. I. p. 113, pi. 

 52, fig. 1. Deljjhinula discors, Fleming, Brit. An. p. 313. 



Shell subdepressed ; with three or four volutions, the larger 

 or body one subimbrieated the whole surface above, covered 

 with wide-set, undulating, transverse stri;c, most conspicuous in 

 passing over the spiral carina;, and producing a cord-like appear- 

 ance ; and with five spiral, rather prominent, rounded ribs on 

 the superior portion of the volutions, which rise a little above 

 the body, and the two superior ones terminating in a flattened, 

 truncated surface; base of the body volution smooth, large, and 

 rounded ; the other volutions small, with a deeply umbilicatcd 

 centre. 



Found in the Carboniferous Limestone, Colebrook Dale. 



7. E. BUGOSUS. — The Wrinkled Euomphalus, pi. XLIL fig. 

 34, 35. 



Euomphalus rugosus. Sowerby, Min. Conch. L p. 113, pi. 

 52, fig. 2. Delphinula rugosa, Fleming, Brit. An. p. 313. 



Shell with three or four depressed volutions; with four spiral 

 ribs above, crossed by oblique, wide-set, undulating strong striae 

 which are stronger as they pass over the ribs, the lower one of 

 which forms an acutely carinatod margin to the body volution ; 

 under surface of the body with strong, irregular, transversely 

 curved plaits, and deeply umbilicated ; aperture subovate, 

 acutely pointed at the carina, and where it forms a junction 

 with the body. 



This species will be easily recognised from tlie E. discors, by its 

 plaited under surface. 



Found in the Carboniferous Limestone of Colebrook Dale. 



8. E. CRISTATUS. — The Crested Euomphalus, pi. XLIL 

 fig. 3G. 



Euomphalus ciistatus. Phillips, Geo. of Yorkshire, II. p. 

 225, pi. 13, fig. 5. 



Shell with three, widely separated, rather smooth volutions, 

 nearly equally rounded on both sides; the exterior margin pro- 

 vided with a scries of alternately large and somewhat smaller, 

 conical, recurved, rather sharp tooth-like processes, which 

 extend to the inner volution. 



Found in the Mountain Limestone at Bulland. 



0- E. NODOsus. — The Knotty Euomphalus, pi. XLII. fig. 

 37, 38. 



Euomphalus nodosus. Sowerby, Min. Conch. I. p. 09, pi. 

 46, fig. 1, 2. Delphinula nodosa, Fleming, Brit. An. p. 313. 



Shell depressed, rather smooth, consisting of four volutions ; 

 the upper side with a nearly central, elevated, rounded spiral 

 ridge; under surface with a central, spiral scries of ovate, rather 

 large, nodular elevations ; these continue in the lower side of 



all the volutions, but are only here visible, as the volutions 

 conceal the external sides of each other to that extent ; aper- 

 ture nearly orbicular, the side next the body being a little 

 square ; under surface forming a cup-shaped hollow cone. 

 Found in the Carboniferous Limestone of Derbyshire. 



10. E. niFRONs. — The Double-fronted Euomphalus, pi. 

 XLII. fig. 39. 



Euomphalus bijrons. Phillips, Geo. of Yorkshire, II. p. 

 225, pi. 13, fig. 4. 



Shell with three rounded volutions ; with a spiral series of 

 nearly orbicular, prominent tubercles above, and obtusely angu- 

 lated and umbilicatcd below. 



Found in the Mountain Limestone at Bolland. 



11. E. ruGiLis The Champion Euomphalus. 



Euomphalus pugilis. Phillips, Geo. of Yorkshire, p. 225. 

 Volutions tuberculate on both sides, which distinguishes it 



from the E. hifrous, to which it otherwire bears a strong 

 resemblance. 



12. E. coRONATUS. — The Crowmed Euomphalus, pi. XLII. 

 fig. 20, 21,22. 



Euomphalus coronatus. Sowerby, Min. Conch. V. p. 71, 

 pi. 450, fig. 3. 



Shell discoidal, quite flat above, the volutions being ranged 

 on the same plain; the margin provided with a carina of broad, 

 flat, slightly pointed, sharp spines ; volutions below, rounded, 

 and deeply concave, terminating in a central umbilicus. 



Found at Ancliffc. 



Genus XXXVIII.—SCALAllIA.— Zawarc/i. 



Shell turreted, elongated, with gibbous, deeply defined 

 volutions, quite apart in some species, j)rovide(l with 

 longitudinal, oblique, acute ribs, which in some instances 

 are so thickened as to become distinctly varicose, in one 

 or two instances, however, they are barely elevated 

 above the surface of the shell ; aperture nearly orbicular, 

 but generally somewhat longer than broad, its margin 

 thickened all round and reflected, and more so in such 

 species where the volutions are separated ; on one side, 

 the lower part of the columella assumes the appearance 

 of an indistinct canal, which is more consj)icuous in some 

 species than in others ; operculum thin, and cornuous. 



1. S. FRONDOSA. — The Leafy Scalaria, pi. XLII. fig. 1. 

 Scalaria frojidnsa. Sowerby, Min. Conch. VI. p. 149, pi. 



577, fig. 1- 



Shell conical, turrolcd, elongated; with seven or eight deeply 

 divided, distinct, smooth volutions; each covered with about 

 twelve longitudinal, membranaceous, very thin, recurved, very 

 uniform ribs, with their superior portions extending above the 

 upper margins of the volutions in the form of concave spines. 



This beautiful species is found in the Suffolk Crag. 



2. S. roLiACEA The Foliated Scalaria, pi. XLII. fig. 2. 



Scalaria J'oliacea. Sowerby, Min. Conch. IV. p. 125, pi. 



390, fig. 2. Fleming, Brit. An. p. 312. G. B. Sowerby, 

 Genera of Shells, No. 1 1 . 



