figured in Phillips's ' Geology of Yorkshire.'' 475 



2. Euomphalus catillus, Martin (Phill. p. 225, t. 13. 

 figs. 1,2). 



The figure is drawn from a much fractured example, the 

 breaks not being shown in the figures. The leading character 

 of this species is the equally angulated ridge on each side of 

 the back ; at least it is said by most writers to be equal, 

 although that on the lower or non-umbilicate side is usually 

 somewhat sharper than the other, which has a tendency to 

 become a little rounded like a marginal cord. The points of 

 difference between this shell, E. calyx, and E. pentangulatus 

 respectively have been well expressed by M'Coy. The 

 section is quadrate, the back being the longest of the four 

 sides. It is the 



Helicites catillus, Martin, Petr. Derb. 1809, t. 7. figs. 1, 2. 

 Euomphalus catillus, J. Sow. Min. Conch. 1814, i. p. 98, t. 45. figs. 3, 4; 



Phillips, he. cit. ; De Koninck, Animaux Foss. p. 427, t. 24. fig. 10, 



a, b ; Goldfuss, Petr. Germ. pt. 3, p. 87, t. 191. fig. 6, a-d. 

 Straparollus? catillus, M'Coy, Brit. Pal. Foss. 1853, fasc. 3, p. 538. 

 Euomphalus catillus, Morris, Cat. Brit. Foss. ed. 2, 1854, p. 247 ; 



Eichwald, Lethsea Rossica, I860, ii. p. 1153 ; De Koninck, Mon. 



Foss. Carb. Bleiberg, 1873, p. 103, t. 4. fig. 4. 



3. Euomphalus calyx, Phillips (p. 225, t. 13. fig. 3). 



The umbilicus in this shell is not so definitely shown as 

 represented in the figure ; it is more or less obscured by matrix, 

 whilst the opposite side of the specimen is wholly imbedded 

 in the limestone. Prof, de Koninck* is quite in error in 

 referring this species to E. catillus, Phill. ; it is in no way a 

 cast " of the spire of a specimen of E. catillus, 11 the true 

 shelly matter being retained over the whole of the specimen. 

 The figures and descriptions of J. de C. Sowerby and Prof. 

 M'Coy are quite conclusive on this point. The aperture is 

 here more nearly triangular than in the last species, although 

 it is decidedly four-sided. It is the 



Euomphalus calyx, Phillips, loc. cit. ; J. de C, Sow. Min. Conch. 1844, 

 vii. p. 47, t. 033. figs. 8-10 ; Brown, Foss. Conch. 1849, p. 81, t. 42. 

 fig. 23. 



Euomphalus tabulatus, De Koninck, Animaux Foss. p. 429, t. 24. fig. 11. 



Straparollus ? calyx, M'Coy, Brit. Pal. Foss. 1853, fasc. 3, p. 537. 



Euomphalus calyx, Morris, Cat. Brit. Foss. 1854, ed. 2, p. 247. 



4. Euomphalus bifrons, Phillips (p. 225, t. 13. fig. 4). 



The Gilbertson collection contains three very well-marked 

 examples of this shell. Phillips describes his species as with 

 " whorls carinato-tuberculated above, obtusely angulated or 



* Animaux Fossiles, p. 428. 



