24 DESCRIPTION OF 



PLATE XXIII. 



P'lgf 



Fig. 1. RETZIA VERNEUILANA. 657 



1 a, b. Ventral and dorsal views of a small individual. 

 1 c. Dorsal view of a more elongate specimen. 



1 d. Enlarged figure of the same. 



Fig. 2. RHYNCHONELLA MUTATA. 658 



2 a, b. Dorsal and ventral views of a specimen of ordinary siae. 



Fig. 3. RHYNCHONELLA SUBCUNEATA. 658 



3 a, b. Ventral and dorsal views of a specimen. 



3 c. Profile of the same. 



Figs. 4 & 5. TEREBRATULA TRINUCLEA. 659 



4 a, b. Dorsal and ventral views of a specimen of the ordinary form. 



4 c. Profile of the same. 



5 Dorsal view of a broader form, showing a wide mesial lobe, with a nar- 



row impression down the centre. 



Fig. 6. SPIRIPER SUBCARDIIPORMIS. 660 



6 a. Ventral valve, the specimen a little distorted from pressure. 



6 b. Dorsal view of the same, showing the area and foramen of the opposite 



valve. 



Fig. 7. SPIRIFER LATERALTS. 661 



7 a. Dorsal view, showing the area and foramen of the ventral valve. 



7 b. Ventral valve of the same specimen, showing the broad undefined 

 mesial depression. 



7 c. Front view, showing the outline and elevation of the mesial fold. 



Fig. 8. SPIRIPER TENUICOSTATOS. 662 



8 a. Dorsal view, showing the beak and part of the area and foramen of the 



opposite valve. 



8 b. Ventral valve, in which the lines of growth and concentric stria; are 



well preserved. 8 c. Profile view of the same. 



Fig. 9. SPIRIPER SUBEQUALIS. 663 



9 a. View of the ventral valve. 



9 b. Dorsal valve, showing the beak of the opposite valve rising a little 

 above the other. 



9 c. Cardinal view, showing the area and foramen. 



Fig. 10. CYPRICARDELLA NUCLEATA. 663 



10 a, b. Dorsal view, and view of the right valve. We. The same enlarged. 

 10 d. Enlargement of the cencentric striae. 



Figs. 11 & 12. CYPRICARDELLA SUBELLIPTICA. 664 



11. View of the right valve. 



12. Interior of the same, showing the character of the hinge-line. 



Fig. 13. PLEUROTOMARIA WORTHENI. 664 



13 a. View of the summit, natural size. 

 13 b. Profile view, showing the elevation of the spire. 

 13 c. View of the base. 



13 d. Enlargement of the stria; and carinations which characterize the surface. 



Fig. 14. CAPULUS ACUTIROSTRIS. 665 



14 a, b. Views of the upper and lower sides of the shell. 



Fig. 15. BEI.LEROPHON SUBL^EVIS. 666 



15 a. View of the aperture. 15 b. Lateral view of the shell. 

 15 c. Dorsal view of the same. 



Fig. 16. DENTALIUM PRIMARIUM. 666 



16. Lateral view of the specimen, natural size. 



