CONTENTS 



Page 



Introduction 7 



The family Pleurotoinariidae 7 



Genus Yvania Bayle (Baylea de Koninck) 8 



Genus Yvania Bayle emend. Weller 10 



Genus Hypselentoma Weller, n. gen 10 



Relations of Yvania 11 



Grouping of American species 11 



Species tentatively referred to Yvania 12 



Descriptions of species 13 



Yvania inclinata Weller, n. sp IS 



Description 15 



Remarks 17 



Occurrence 17 



Yvania pusilla Weller, n. sp 17 



Description • 17 



Remarks 19 



Occurrence • 20 



Yvania gurlcyi (Meek) 20 



Description 20 



Remarks 22 



Occurrence • 22 



Yvania supercrenata Weller, n. sp 22 



Description • 22 



Remarks 25 



Occurrence 25 



Yvania knighti Weller, n. sp 25 



Description 25 



Remarks 27 



Occurrence 27 



Yvania salinensis Weller, n. sp 27 



Description • 27 



Remarks 29 



Occurrence 29 



Yvania adanisi (Worthen) 30 



Description 30 



Remarks 32 



Occurrence 32 



Yvania subconstricta (Meek and Worthen) 32 



Description • 32 



Remarks 35 



Occurrence 3S 



