PLATE 95 A. 



I'age 



Fig. 1. RnYNcnosPiRA rectirostra. 485 



1 a, b, c. Dorsal, ventral and profile views of a sp2cimen of this species. 



Fig. 2, 3, 5 & 6. Merista (Camariom) typuji, 487 



2 a. Dorsal view of a specimen of this species. 

 2 b. Profile view of the same. 



3. Interior of the ventral valve, showing the transversa arching septum. 



6. A longitndinal section of fig. 3. 



0. A cast of the interior of a valve similar to fig. 3. 



Fig. 4. Merista (Camarium) elongatum. 488 



4. The interior of a ventral valve of tlii.i species : the sides of the valve, and a part of tho 



arching septum, have been broken away. 



Fig. 7 - 11. Rhynciiospira Formosa. 486 



7. Interior of the ventral valve of a specimen of this species. 



8. I iterior of the dorsal valvo, enlarged to two diameters, to show the broad cardinal process 



which covers the extremities of the beak. and. when tho valves are closed, passes beneath 

 the deltidial area of the opposite valve. The bases of the crura are shown on each side at 

 the base of the cardinal process, and the short median septum also is shown. 



9. Profile view of the same, showing the cardinal and crnnal processes. 



10. Tlie upper part of the two valves connected in their natural relations to each other, and 



showing the manner of articulation. 



11. A longitudinal section, showing the foramen, the deltidium, and the cardinal process of 



the ojiposite viilve lying beneath it; the crura first bending downwards, and then re- 

 curved into the dorsal valve and continued in the spire, witli the descending process e, 

 which forms, with the opposite one, a coimecting filament between the two spires. 



Fig. 1-3 & 14. STROPnODONTA INTERMEDIA*. 482 



13. The exterior of the dorsal valve. 



14. The interior of the same. 



Fig. 15 - 19. STROPnODONTA MAQNIFICAt. 482 



15. A dorsal view, showing the area, which is imperforate and striate. The specimen is below 



the medium size which this shell usually attains. 



16. Ventral view of the same : tlie margins are broken, and the outline is consequently im- 



perfect . 



17. The interior of a ventral viilve of the same species, showing a central pit or foramen. 



18. View of the area when the linear foramen is closed. 



19. Enlargement of the stria;, showing their mode of bifurcation, and the puncta which are 



very regularly interposed between the stria;. 



Fig. 20 & 21. Orthis cu.mberlandia. 481 



20. The exterior of a ventral valve of this sjjecies. 



21. The interior of a smaller ventral valvo of the same. 



• This species possesses the cardinal process of Stropiiodoxt.v, with the dental lamella; of STREPTORnvNcncs. 



f This species may be compared with Orthis hipparinnyTt page 407. The striae, however, are more sharply elevated  ^ 



and less curved towards the binge-line, while the muscular Impression is uut distinctly bilobatc as in that species. S 



