CLASS IV 



GASTROPODA 



551 



and body whorl often retaining traces of apertures at earlier stages. Veiy abundant 

 in Jura and Cretaceous. 



Subgenera : Dicrolovm Gabb ; Anchura Conrad (Fig, 987). 

 Cretaceous. Diempterus Piette. Jura. 



Jura and 



Fig. 987. 



Alaria myuras Desloiii;ch. 

 Lower Oolite ; Bayeux, Cal- 

 vados. 



Fi(!.'!t86. 



Alaria annata Morris 



and Lye. Great Oolite ; Alaria (Aiichura) cari- 



Minchinhanipton, Eng- nata Mant. Gaiilt ; 



land. I Folkestone, England. 



Fig. 988. 



Sp in igc ra semica rinata, 

 (Goldfuss). Callovian ; 

 Montrei\il - Bellay, 

 Maine-et-Loire. 



Spinigera d'Orl). (Fig. 988). Whorls keeled and ornamented with two opposite 

 rows of spines. Jura. 



Aporrhais Ba, Costa {Ghenopvs Phil.) (Figs. 

 989-991). Like Alaria, but niai'gins of aperture 

 elongated posteriorly in a canal, whicli remains 

 either attached to the spire, or extends free from 

 the same. Outer lip expanded, digitated or lobed. 

 Jura to Recent. 



Subgenera : Alices Conrad ; Arrhoyes, Tessarolax, 

 Hclicaulax Gabb ; Ceratosi'phon Gill ; Cuphosclenus, 

 Malaptera Piette ; Pterocercl la Meek ; Dimorphosoma 

 St. Gardner (Fig. 990) ; Lispodesthes White (Fig. 

 991). Jura and Cretaceous. 



\^v 



Fig. 989. 



Aporrhais tridactijhis A. Braun. Oligo- 

 ceiie ; Hackenlieim, near Creuznach. 



Fig. 990. 



Aporrhais {Dimor- 

 phosoma) calcarata 

 8 o w b. Upper 

 Greensand ; Black- 

 down, England. 



Fig. 991. 



Aporrhais (Lispochsthcs) rcuasl Geinitz 



var. megaloiitera Reuss. 

 Bohemia. 



Planer ; Postelberg, 



Family 19. Strombidae d'Orbigny. 



Shell conical, turreted or fusiform, ivith acuminate spire. Aperture canaliculate ; 

 outer lip often expanded, anteriorly with an emargination. Opercuhim horny. Jura 

 to Recent. 



Although the shells of this family are excessively variable, the soft parts of the 

 animals exhibit great uniformity of structure. 



