XIV 



DIOTOCARDIA — RHIPIDOGLOSSA 



409 



surface spirally Urate, scaly, spinose, umbilicate, peristome con- 

 tinuous. Single genus, Delpliinula. (iv.) Umhoniinae. — Eyes 

 pedunculate, left tentacle attached to a frontal appendage, mantle 

 reflected over edge of aperture, lateral teeth 6 on each side ; 

 shell polished, peristome incomplete, umbilicus generally closed 

 by a callosity. Principal genera: Umhonium^ Ethalia^ Isanda^ 

 Camitia, Umhoiiella^ Chrysosto^na. 



Fam. 6. Turhinidae. — Epipodial line with slender cirrhi, snout 

 broad, short, eyes pedunculate at outer base of tentacles, a frontal 

 veil between tentacles; shell turbinate, solid, aperture continuous, 

 operculum solid, calcareous, usually paucispiral, convex exteriorly 



(Fig. 182, p. 268). Silurian . (i.) Phasianellinae. — Shell 



bulimoid, polished, not nacreous, coloured in patterns, aperture 

 oval. Single genus, Phasianella (Fig. 271). (ii.) Turhininae. — 

 Shell very solid, nacreous within, aperture circular or long oval. 

 Principal genera, Turho^ whorls rounded above and below, spines, 

 if present, becoming more prominent with age, operculum smooth 

 orgranulose, nucleus sub-central; subg. Callopoma^ Ninella^ Mar- 

 morostoma^ Sarmaticus^ P risog aster ; Astraliitm^ whorls flattened 

 above and below, spines, if present, becoming less prominent with 

 age, operculum oblong, often excavated at centre, last whorl large, 

 nucleus marginal or sub-marginal ; subg. Llthopoma^ Imperator^ 

 Gruildfordia^ Bolma^ Oyclocantha^ Uvanilla, 

 Cookia^ Pomaidax^ Pachypoma. (iii.) Cyclo- 

 nematinae. — Shell nacreous, umbilicate, 

 operculum conical outside, whorls scalari- 

 form. Principal genera: Cyclonema^ Hori- 

 ostoma (?), Amherleya (Silurian to Lias), 

 (iv.) Leptothyrinae. — Shell small, solid, de- 

 pressed, operculum nearly flat, nucleus sub- 

 central. Genera: Leptothyra^ CoUo7iia (?). 



Fam. 7. Neritopsidae. — Tentacles wide 

 apart, long, eyes on short peduncles at the 

 outer base; shell solid, neritif orm or naticoid, 

 aperture semi-lunar or oval; operculum 

 (Fig. 183, p. 269) thick, calcareous, non- 

 spiral, exterior face smooth, interior face 

 divided into two unequal parts, with a broad 



median appendage. Devonian . Principal genera: Neri 



topsis (one recent species), Naticopsis (Devonian to Miocene). 



Fig. 271. — Phasianella aus- 

 tral is Grael., Australia. 



