482 



MOLLUSCA 



SUB- KINGDOM VI 



is characterised by a line running parallel with the suture, and creating a narrow 

 suture band. 



Family 3. Pleurotomidae. Stoliczka. 



Shell fusiform) with moderately high spire. Aperture elongated, produced anteriorly 

 in a longer or shorter canal. Outer lip with a slit or notch below the suture. Operculum 

 horny, sometimes absent. Cretaceous to Recent. 



Upwards of 700 recent and 1000 fossil species have been described, of which 28 

 are Cretaceous. 



Pleurotoma, Lam. (Figs. 995-998). Shell turriculated, spire long. Body whorl of 

 nearly equal length with the spire ; canal long and straight ; columellar margin 



A V C A 



FIG. 995. 



A, Pleurotoma notata, Brocchi var. ( = P. monilis, 

 Hoernes). Miocene ; Baden, near Vienna. B, P. (Surcula) 

 Lamarcki, Bell. Miocene ; Baden, near Vienna. C, P. 

 (Surculct) belgica, Nyst. Oligocene ; Weinheim, near 

 Alzey. 



FIG. 



A, Pleurotoma (Genota) ramosa, 

 Bast. Miocene ; Grund, Hungary. 

 B, P. (Cryptoconus) filosa, Lam. 

 Calcaire Grossier; Grignon, near 

 Paris. 



smooth. Outer margin of the aperture with a narrow, deep sinus, situated at or some 



distance below the suture. 

 Operculum pointed ovate, 

 with apical nucleus. Cre- 

 taceous to Recent. 



Sub-genera : Surcula 

 (Figs. 995, B, G] ; Genota, 

 Adams (Fig. 996, A); Doli- 

 chotoma (Fig. 997), Oligo- 

 toma, JRoualtia, Bellardi ; 

 Cryptoconus, v. Koenen 

 (Fig. 996, B} ; Drillia (Fig. 

 998), Beta, Gray ; Lachesis, 

 Risso, etc. 



Clavatula, Lam. (Fig. 

 9 9 9). Differs from Pleuro- 

 toma in that the outer 

 margin is cut by a shallow 

 triangular notch, and 

 nucleus of operculum is 

 situated in the middle of 

 Sub-genera : Pseudotoma, Clinura, 



FIG. 997. 



Pleurotoma (Dolicho- 

 toma) cataphracta, 

 Brocchi. Miocene ; 

 Baden, near Vienna. 



FIG. 998. 



Pleurotoma (Drillia) 

 incrassata, Duj. Mio- 

 cene ; Steinabrunn, 

 near Vienna. 2 /j. 



FIG. 999. 

 Clavatula asperulata, 



the anterior margin. 

 Bellardi. 



Cretaceous to Recent. 



