JOPRNAI. OF CONCHOI.OGY, Voi,. 1 5, Nd. 9, MaV 1ST, I918. 



Plate 5. 



Orifice 



Inner margin 



8 appvoN 



Oiitei' lolje 

 Inner loIje 



Proximal end 



Pedicle 



SrAlt'LA 



Onler margin 

 I>islal t-nd 



The Ci.ausiu.m ix Clausilia. 

 illustrating ihr tiokm.s used in defining a clau.sium. 



(Internal aspect). 



Types of the Clausium. 



Ku;. I 



Biluljatf. 



I'^iiiHrginalc. 



Rfrte.xed. 



Reflexed ( Gaiiiicria). 



Kostrale. 



In;. 6. Truncate. 



,, 7. Infle.Ncd and Truncate. 



., 8. Inflexed. 



,, 9. Clavate. 



,, 10. Remifomi. 



