PLATE 36. 
Legend: t. Teeth. c. Crura. 
hp. Hinge-plate. b. Dental sockets. 
s. Median septum. 
KAYSERIA, Davinson. 
Page 765. 
KaysEria LENS, Phillips. 
Figs. 1, 2. Dorsal and profile views of an average example. X 2. 
Middle Devonian. Eifel, Germany. 
RETZIA, Kine. 
Page 787. 
Retzta ApRIENI, de Verneuil. 
Figs. 3, 4. Ventral and dorsal views of the exterior. 
Fig. 5. Ventral view of ashell from which a portion of the brachial valve 
has been exfoliated; showing the median septum and a portion of 
one spiral. 
Fig. 6. An enlarged view of a shell which has been transversely sectioned in 
the umbonal region; showing the hinge-plate, dental sockets and 
median septum. 
Fig. 7. Dorsal view of the umbonal region of conjoined valves; showing the 
broad cardinal slopes of the pedicle-valve and the coalesced del- 
taria. X 2. 
Lower Devonian. Department de la Sarthe, France. 
(Figs. 5, 6, G8HLERT.) 
RHYNCHOSPIRA, Hatt. 
Page 791. 
RuyNcHosPira Formosa, Hall. 
Fig. 8. A dorsal view of a typical specimen. 
Fig. 9. The interior of the cardinal portion of a pedicle-valve ; showing the 
circular foramen and the completely coalesced deltaria. X 2. 
Fig. 10. The interior of a pedicle-valve. 
Fig. 11. The interior of a brachial valve ; showing the form of the hinge-plate. 
Fig. 12. An interior view of the cardinal portion of articulated valves ; show- 
ing the elevation of the hinge-plate and the median septum of the 
brachial valve. 2. 
Lower Helderberg group. The Helderbergs,"N.°Y. 
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