Victorian Fossils, Part XIX. 89 



the figure. In the earlier whorls of other specimens the band is 

 distinctly depressed and bounded above and below with a raised 

 thread. The longest example, but imperfect, of this fine species 

 in our collection measures 70 mm. 



Occurrence. — Silurian (Yeringian). In limestone. Cave Hill, 

 Lilydale. Collected by the Rev. A. W. Cresswell, M.A., who pre- 

 sented the type specimen. 



Fam. EUOMPHALIDAB. 



Genus Euomphalus, Sowerby. 



Euomphalus centrifugalis, sp. nov. (Plate IV., Figs. 30, 31 ; 

 Plate VI., Figs. 54, 55). 



Description. — Shell compressed, planorbiform. Outline discoidal, 

 but tending to irregular growth; sometimes almost subovate in out- 

 line. Superior face gently convex and sloping to the periphery on 

 the last whorl, the inner series excavate; inferior face flat on the 

 periphery and concave towards the centre. Spire visible on both 

 .sides and evolute. Aperture compressed, pyriform. Surface of 

 whorls marked by numerous strong, sharply deflected growth-lines. 



Dimensions. — Holotype. Greatest diameter, 14 mm. ; at right 

 angles, 10.5 mm. Width of last whorl, 4 mm. Approximate thick- 

 jiess of shell, 2.25 mm. 



Observations. — This species bears some resemblance to E. declivis, 

 Remeles,! of the Lower Silurian limestone obtained from the 

 •diluvium deposit of North Germany; especially in the sinuate and 

 oblique character of the growth-lines. In that species, however, the 

 whorls are not so deeply concave, and the body whorl tends to 

 laecome an open spiral. 



In general appearance Lindstrom's Oriostoma dispar may be 

 mentioned, 2 which, by the way, is probably a true Euomphalus 

 •species. In this form, however, the outer whorl is not so highly 

 ■convex on the inner side nor so steeply sloping to the periphery. 

 Lindstrom's shell, being a Gotland species, comes from a bed of 

 .similar age as the above. 



E. centrifugalis appears to be a thin-shelled ancestor of the 

 Euomphalus catillus type,^ a compressed and striate species well 

 known as a Carboniferous limestone fossil. 



1 Zeitschr. d. deutsch. geol, Gesellsch, vol. xl., 1888, p. 669, pi. xxviii., fig. 3. 



2 Kongl. Svenska Vet.-Akad. Handl., Bd. xix., No. 6, 1S84, p. 173, pi. xxi., figs. 11-14. 



3 Min. Conch., toI. 1, 1814, p. 98., pi. xlv., figs. 3, i. Phillips' Geol. Yorkshire, vol. ii., 1836, 

 •pi. xiii., figs. 1, 2. 



