PLATE 53. 
Legend: F. Foramen. m. Muscular platform. 
p. Pedicle-groove. fc. Foraminal sheath. 
d. Dental plates. D. Deltaria. 
BEECHERIA, Hatt. 
Page 866, 
Brrcueria Davinsont, Hall. 
Fig. 1. The internal cardinal structure exposed by the removal of a portion 
of the pedicle-valve; showing the absence of dental plates in this 
valve and the structure of the loop. 3. 
Figs. 2, 3. Dorsal and profile views of an average example. 
Carboniferous limestone. Windsor, Nova Scotia. 
CRAN AINA, Hatt. 
Page 865. 
Cranana Romineert, Hall. 
Figs. 4, 5, 6. Dorsal, ventral and profile views of a typicalexample. X 2. 
Hamilton group. Thunder Bay, Michigan. 
Crana=na lIowenis, Calvin. 
Figs. 7, 8. Dorsal and profile views of a normal individual. 
Hamilton group. Rockford, Iowa. 
Fig. 9. A preparation showing the structure of the loop, the ascending 
branches being partially retained. X 2. 
Hamilton group. Fayette, Iowa. 
DIELASMA, Kine. 
Page 863. 
DretasMA TuRGIDA, Hall. 
Fig. 10. Dorsal view of a specimen having a single plication in the sinus of the 
pedicle-valve. x 1}. 
Fig. 11. Dorsal view of an example with broad median sinus. X 2. 
Chester limestone. Spencer county, Indiana. 
Fig. 12. Profile of an old shell with highly ventricose valves. 
St. Louis group. Washington county, Indiana, 
264 
