P L .A. a^ K 1 1 I . 



Fi;;. 1. Snuii'Ki; Utaiiknsis 3'J 



1. Au antero-voutral view, natural sizo. 

 1 a. Dorsal view of same specimen. 



1 ft. A side view of a smaller specimen. 



1 c. A cardinal view of another specimen, showing area and foramen. 

 1 d. Cardinal view of the ventral valve of the largest specimen seen. 

 1 e. Au autero-ventral view of same. 



Fig. 2. Hkmii'uonites Ciiemungensi.s, mr. ahctostriata S.'i 



2. View of ventral valve, with au oblique view of area. 



Fig. 3. SPiitiFEU Engelmanni 41 



3. A cardinal view, .showing area and foramen. 

 3o. A side view of .saml^ 



3 b. Dorsal view of same. 



3 c. An aiitero-ventral view. 



3 rf. A ventral view of another specimen appareutlj' of this species. 



3 e. Dorsal view of last. 



Fig. 4. Sl'IIUl-EI! ARGENTARIUS 42 



4. A ventral view. 



4 a. Cardinal view of same specimen, showing its low, strongly iucnrvid area, foramen, 



etc. 



4 6. A dorsal view of same. 



Fig. 5. Spiiui'eu stkigosus 43 



.'">. View of ventral valve. 



5 a. View of dorsal valve. 

 5 6. Profile view of same. 



Fig. 0. AriiYPA heticularis 38 



t;. Ventral view. 



(iu. Dorsal view of another specimen with finer striio. 



Fig. 7. Pkoductus suhaculeatus ? 3:5 



7. Ventral view. 



7 a. Ventral view of another more elongated specimen. 



7 h. A cast of the exterior of a dorsal valve of same. 



Fig. 8. POSIDO.NO.MVA ? KUAGOSA 92 



8. A left valve, flattened by pressure between tho lamiuie of shale, with the edges 



about the beak incomplete. 



8 a. A smaller right valve flattened iu the same way, and showing indicaliuiis of a small 



anterior ear-like projection. 



Fig. y. LeIOUU YNCIIUS ? QUADKICOSTATU.S 79 



9. Au internal cast of a ventral valve, Uatteued by pressure. 

 9n-h. Internal casts of two dorsal valves, somewhat compressed. 



Fig. 10. AVICULOI'EOTICN CATACTUS 93 



10. A left valve, somewhat enlarged. 

 10 a. Another left valve, natural size. 



10 6. Aright valve, apparently of this species, enlarged about two diameters ; much of 



its pallial margin being broken away. 



Fig. 11. SfllUKKIt (SVRINGOTIIYUIS) CUSPID.VTU.S 87 



11. A cardinal view, showing the high area and foramen, and, within tlie latter, tlio 



transverse septum and internal tube. 



11 a. An aiil(Tior view of >:inii'. 



