PLATE 31. 
Legend: D. Deltarium. j. Cardinal process. 
t. Teeth. b. Dental sockets. 
s, 8’. Median septum. c. Crural bases. 
x. Hinge plate. 
SPIRIFERINA, p’Orsieny. 
; Page 764. 
SPIRIFERINA TRANSVERSA, McChesney. 
Fig. 1. Dorsal view of an entire specimen ; showing the general proportions 
and the lamellose exterior. 
Chester limestone. Buzzard’s Roost, Alabama. 
Fig. 3. Oblique view of the interior of a pedicle-valve ; showing the median 
septum. 
Carboniferous limestone. IJtaituba, Brazil. 
SPIRIFERINA SUBELLIPTICA, McChesney. 
Fig. 2. The interior of a portion of the brachial valve ; showing the articu- 
lating apparatus, elevated muscular ridges and low median septum. 
x2. 
Keokuk group. New Providence, Indiana. 
SPIRIFERINA SPINOSA, Norwood and Pratten. 
Fig. 4. A median longitudinal section through conjoined valves; showing 
the elevation and extent of the median septum. 
Figs. 5, 6. Dorsal and ventral views of a normal example. 
Fig. 7. An enlargement of the external surface ; showing the bases of spinules 
and the puncte of the shell. 
Chester limestone. Chester, Illinois. 
AMBOCGCSLIA, Hatt. 
Page 761. 
AMBOC@LIA UMBONATA, Conrad. 
Figs. 8, 9,10. Dorsal, ventral and profile views of anormal shell. x 2. 
Fig. 11. The interior of a pedicle-valve, enlarged. 
Fig. 12. The interior of a brachial valve, showing the low cardinal process, 
high crural plates and conspicuous adductor scars. 
Fig. 18. A preparation showing the form of the spiral cones. 
Hamilton group. Western New York. 
214 
