EXPLANATION OF PLATE I 

 All figures are enlarged four diameters 



Fig. 1. Yvania inclinata Weller, n. sp p. 15 



The holotype. 



Figs. 2a-3. Yvania supercrenata Weller, n. sp p. 21 



2a, b. The holotype. 

 3. A paratype. 



Figs. 4a-c. Yvania pusilla Weller, n. sp p. 17 



The holotype. 



Figs. 5-8. Yvania knigiiti Weller, n. sp p. -25 



5. The holotype. 



6-8. Paratypes. The basal view shows a specimen whose outer costae are 

 more widely spaced than usual. 



Figs. 9-10c. Yvania salinensis Weller, n. sp p. 27 



9. A paratype. 

 lOa-c. The holotype. 



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