PLATE 10. 



Fig. 1. Pteria (Oxytoma?) gastrodes r. 280 



a. View of sandstone cast of left valve ; natural size. 



Fig. 2. Pteria (Pseudoptera) propleura 281 



a. Left valve of young example; front margin not quite perfect. 



b. Left valve of a somewhat larger example. 



c. Left valve of adult example; drawn from a gutta-percha cast 



of the sandstone mould of Mr. Meek's type-specimen of his 

 Avicula {Pseudoptera) rlrytopl\ora\ 



Fig. 3. Baroda wyomingensis , , . 293 



a. Left valve; natural size. 



b. Dorsal view of the same example. 



Fig. 4. Baroda subelliptica 294 



a. Lateral view ; left valve ; natural size. 



b. Dorsal view of the same, showing dorsal aspect of the teeth. 



c. Right side view of a smaller example. 

 cl. Dorsal view of the same. 



Fig. 5. Trapezium micronema , . . - . 293 



a. Left side view ; natural size. 



Fig. 6. Trapezium truncatum 292 



a. Left side view ; natural size. 



b. Dorsal view of the same specimen. 



Fig. 7. Oyrena inplexa 290 



a. Lateral view; right valve; natural size. 



b. Natural cast of right valve, showing muscular impressions and 



pallia! line and sinus. 



