FLA TE XXV. 



BOLUS CONRADI, HaLL. 



Page 375. 



Fig. 1. Interior of a ventral valve, made from a cast in the natural mould. 

 " 2. Interior of a smaller ventral valve, obtained by the same process as fig. 1. The dotted 



lines show the extent of the cavities beneath the transverse plate. 

 " 3. Interior of a dorsal valve, taken from a gutta-percha cast in the natural mould. The 



figures 2 and 3 are from the same casts as those figured on plate 13. 



Spirifera plicatella, var. radiata, Sow. 



Page 378. 



Fig. 4. Dorsal view of a large cast, showing the cavities left by the removal of the dental lamellas 

 and the septum of the dorsal valve. 

 " 5. Cardinal view of the same specimen as fig. 4, showing also the extent of the area. 

 " 6. An oblique view of the interior of both valves, showing the septa and dental lamellae. 



Pentamerus (Pentamerella) ventricosus, Hall. 



Page 383. 



Figs. 7, 8. Dorsal and fronf views of an individual, showing the plications more distinctly than 

 usual. 



Pleurotomaria occidens, Hall. 



Page 392. 



Fig. 9. Lateral view of a very fine specimen, showing the external characters of the species. 

 " 10. View of the aperture. This specimen is from the Niagara limestone of Lyons, Iowa, 

 received from Dr. Farnsworth. 



PLEVROT03IARIA {TrOCHONEMA) HOYI, HaLL. 

 Page 393. 



Figs. 11, 12. Lateral and basal views of a specimen of this species, showing the surface striae and 

 the wide umbilicus. 



TrOCHONEMA (CrCLONEMAf) PAUPER, HaLL. 

 Page 395. 



Fig. 13. Lateral view of a specimen in the collection of the Michigan University, at Ann Arbor, 

 received under the name of Pleurotomaria Haiti. 



Cyrtoceras brevicorne. Hall. 



Page 407. 

 Fig. 14. Lateral view of a specimen, showing the septa. 



Trochoceras costatum, Hall. 



Page 402. 

 Fig. 15. Lateral view of the upper surface, from a gutta-percha cast in the natural mould. 



